Commit Graph

8918 Commits

Author SHA1 Message Date
Sergey Zolotukhin
e157e8577e gossiper: check for a race condition in do_apply_state_locally
In do_apply_state_locally, a race condition can occur if a task is
suspended at a preemption point while the node entry is not locked.
During this time, the host may be removed from _endpoint_state_map.
When the task resumes, this can lead to inserting an entry with an
empty host ID into the map, causing various errors, including a node
crash.

This change
1. adds a check after locking the map entry: if a gossip ACK update
   does not contain a host ID, we verify that an entry with that host ID
   still exists in the gossiper’s _endpoint_state_map.
2. Removes xfail from the test_gossiper_race test since the issue is now
   fixed.
3. Adds exception handling in `do_shadow_round` to skip responses from
   nodes that sent an empty host ID.

This re-applies the commit 13392a40d4 that
was reverted in 46aa59fe49, after fixing
the issues that caused the CI to fail.

Fixes: scylladb/scylladb#25702
Fixes: scylladb/scylladb#25621

Ref: scylladb/scylla-enterprise#5613
(cherry picked from commit f08df7c9d7)
2025-09-08 21:54:43 +00:00
Emil Maskovsky
e8b903979e test/gossiper: add reproducible test for race condition during node decommission
This change introduces a targeted test that simulates the gossiper race
condition observed during node decommissioning. The test delays gossip
state application and host ID lookup to reliably reproduce the scenario
where `gossiper::get_host_id()` is called on a removed endpoint,
potentially triggering an abort in `apply_new_states`.

There is a specific error injection added to widen the race window, in
order to increase the likelihood of hitting the race condition. The
error injection is designed to delay the application of gossip state
updates, for the specific node that is being decommissioned. This should
then result in the server abort in the gossiper.

This re-applies the commit 5dac4b38fb that
was reverted in dc44fca67c, but modified
to relax the check from "on_internal_error" to a just warning log. The
more strict can be re-introduced later once we are sure that all
remaining problems are resolved and it will not break the CI.

Refs: scylladb/scylladb#25621
Fixes: scylladb/scylladb#25721
(cherry picked from commit 28e0f42a83)
2025-09-08 21:54:43 +00:00
Calle Wilund
71ef2caef9 system_keyspace: Prune dropped tables from truncation on start/drop
Fixes #25683

Once a table drop is complete, there should be no reason to retain
truncation records for it, as any replay should skip mutations
anyway (no CF), and iff we somehow resurrect a dropped table,
this replay-resurrected data is the least problem anyway.

Adds a prune phase to the startup drop_truncation_rp_records run,
which ignores updating, and instead deletes records for non-existant
tables (which should patch any existing servers with lingering data
as well).

Also does an explicit delete of records on actual table DROP, to
ensure we don't grow this table more than needed even in long
uptime nodes.

Small unit test included.

Closes scylladb/scylladb#25699

(cherry picked from commit bc20861afb)

Closes scylladb/scylladb#25813
2025-09-08 16:26:04 +03:00
Avi Kivity
5de570c9ae Merge 'auth: move passwords::check call to alien thread' from Andrzej Jackowski
Analysis of customer stalls revealed that the function `detail::hash_with_salt` (invoked by `passwords::check`) often blocks the reactor. Internally, this function uses the external `crypt_r` function to compute password hashes, which is CPU-intensive.

This PR addresses the issue in two ways:
1) `sha-512` is now the only password hashing scheme for new passwords (it was already the common-case).
2) `passwords::check` is moved to a dedicated alien thread.

Regarding point 1: before this change, the following hashing schemes were supported by     `identify_best_supported_scheme()`: bcrypt_y, bcrypt_a, SHA-512, SHA-256, and MD5. The reason for this was that the `crypt_r` function used for password hashing comes from an external library (currently `libxcrypt`), and the supported hashing algorithms vary depending on the library in use. However:
- The bcrypt schemes never worked properly because their prefixes lack the required round count (e.g. `$2y$` instead of `$2y$05$`). Moreover, bcrypt is slower than SHA-512, so it  not good idea to fix or use it.
- SHA-256 and SHA-512 both belong to the SHA-2 family. Libraries that support one almost always support the other, so it’s very unlikely to find SHA-256 without SHA-512.
- MD5 is no longer considered secure for password hashing.

Regarding point 2: the `passwords::check` call now runs on a shared alien thread created at database startup. An `std::mutex` synchronizes that thread with the shards. In theory this could introduce a frequent lock contention, but in practice each shard handles only a few hundred new connections per second—even during storms. There is already `_conns_cpu_concurrency_semaphore` in `generic_server` limits the number of concurrent connection handlers.

Fixes https://github.com/scylladb/scylladb/issues/24524

Backport not needed, as it is a new feature.

Closes scylladb/scylladb#24924

* github.com:scylladb/scylladb:
  main: utils: add thread names to alien workers
  auth: move passwords::check call to alien thread
  test: wait for 3 clients with given username in test_service_level_api
  auth: refactor password checking in password_authenticator
  auth: make SHA-512 the only password hashing scheme for new passwords
  auth: whitespace change in identify_best_supported_scheme()
  auth: require scheme as parameter for `generate_salt`
  auth: check password hashing scheme support on authenticator start

(cherry picked from commit c762425ea7)
2025-09-07 14:30:26 +03:00
Pavel Emelyanov
112827b170 Revert "test/gossiper: add reproducible test for race condition during node decommission"
This reverts commit 46f8404100 because
parent PR had been reverted as per #25803
2025-09-05 10:07:10 +03:00
Pavel Emelyanov
ed3e671564 Merge '[Backport 2025.2] drop table: fix crash on drop table with concurrent cleanup' from Scylladb[bot]
Consider the following scenario:

- A tablet is migrated away from a shard
- The tablet cleanup stage closes the storage group's async_gate
- A drop table runs truncate which attempts to disable compaction on the tablet with its gate closed. This fails, because table::parallel_foreach_compaction_group() ultimately calls storage_group_manager::parallel_foreach_storage_group() which will not disable compaction if it can't hold the storage group's gate
- Truncate calls table::discard_sstables() which checks if the compaction has been disabled, and because it hasn't, it then runs on_internal_error() with "compaction not disabled on table ks.cf during TRUNCATE" which causes a crash

Fixes: #25706

This needs to be backported to all supported versions with tablets

- (cherry picked from commit a0934cf80d)

- (cherry picked from commit 1b8a44af75)

Parent PR: #25708

Closes scylladb/scylladb#25784

* github.com:scylladb/scylladb:
  test: reproducer and test for drop with concurrent cleanup
  truncate: check for closed storage group's gate in discard_sstables
2025-09-04 08:44:29 +03:00
Emil Maskovsky
46f8404100 test/gossiper: add reproducible test for race condition during node decommission
This change introduces a targeted test that simulates the gossiper race
condition observed during node decommissioning. The test delays gossip
state application and host ID lookup to reliably reproduce the scenario
where `gossiper::get_host_id()` is called on a removed endpoint,
potentially triggering an abort in `apply_new_states`.

There is a specific error injection added to widen the race window, in
order to increase the likelihood of hitting the race condition. The
error injection is designed to delay the application of gossip state
updates, for the specific node that is being decommissioned. This should
then result in the server abort in the gossiper.

Refs: scylladb/scylladb#25621
Fixes: scylladb/scylladb#25721

Backport: The test is primarily for an issue found in 2025.1, so it
needs to be backported to all the 2025.x branches.

Closes scylladb/scylladb#25685

(cherry picked from commit 5dac4b38fb)

Closes scylladb/scylladb#25780
2025-09-02 20:54:09 +02:00
Ferenc Szili
1bf298c722 test: reproducer and test for drop with concurrent cleanup
This change adds a reproducer and test for issue #25706

(cherry picked from commit 1b8a44af75)
2025-09-02 02:18:21 +00:00
Nadav Har'El
c04b086929 alternator: avoid oversized allocation in Query/Scan
This patch fixes one cause of oversized allocations - and therefore
potentially stalls and increased tail latencies - in Alternator.

Alternator's Scan or Query operation return a page of results. When the
number of items is not limited by a "Limit" parameter, the default is
to return a 1 MB page. If items are short, a large number of them can
fit in that 1MB. The test test_query.py::test_query_large_page_small_rows
has 30,000 items returned in a single page.

In the response JSON, all these items are returned in a single array
"Items". Before this patch, we build the full response as a RapidJSON
object before sending it. The problem is that unfortunately, RapidJSON
stores arrays as contiguous allocations. This results in large
contiguous allocations in workloads that scan many small items, and
large contiguous allocations can also cause stalls and high tail
latencies. For example, before this patch, running

    test/alternator/run --runveryslow \
        test_query.py::test_query_large_page_small_rows

reports in the log:

    oversized allocation: 573440 bytes.

After this patch, this warning no longer appears.
The patch solves the problem by collecting the scanned items not in a
RapidJSON array, but rather in a chunked_vector<rjson::value>, i.e,
a chunked (non-contiguous) array of items (each a JSON value).
After collecting this array separately from the response object, we
need to print its content without actually inserting it into the object -
we add a new function print_with_extra_array() to do that.

The new separate-chunked-vector technique is used when a large number
(currently, >256) of items were scanned. When there is a smaller number
of items in a page (this is typical when each item is longer), we just
insert those items in the object and print it as before.

Beyond the original slow test that demonstrated the oversized allocation
(which is now gone), this patch also includes a new test which
exercises the new code with a scan of 700 (>256) items in a page -
but this new test is fast enough to be permanently in our test suite
and not a manual "veryslow" test as the other test.

Fixes #23535

(cherry picked from commit 2385fba4b6)

Closes scylladb/scylladb#25654
2025-09-01 16:40:02 +03:00
Nadav Har'El
46bd9f2f27 utils, alternator: fix detection of invalid base-64
This patch fixes an error-path bug in the base-64 decoding code in
utils/base64.cc, which among other things is used in Alternator to decode
blobs in JSON requests.

The base-64 decoding code has a lookup table, which was wrongly sized 255
bytes, but needed to be 256 bytes. This meant that if the byte 255 (0xFF)
was included in an invalid base-64 string, instead of detecting that this
is an invalid byte (since the only valid bytes in a base-64 string are
A-Z,a-z,0-9,+,/ and =), the code would either think it's valid with a
nonsense 6-bit part, or even crash on an out-of-bounds read.

Besides the trivial fix, this patch also includes a reproducing test,
which tries to write a blob as a supposedly base-64 encoded string with
a 0xFF byte in it. The test fails before this patch (the write succeeds,
unexpectedly), and passes after this patch (the write fails as
expected). The test also passes on DynamoDB.

Fixes #25701

Signed-off-by: Nadav Har'El <nyh@scylladb.com>

Closes scylladb/scylladb#25705

(cherry picked from commit ff91027eac)

Closes scylladb/scylladb#25765
2025-09-01 09:07:00 +03:00
Calle Wilund
a2bc1a7c6b commitlog: Ensure segment deletion is re-entrant
Fixes #25709

If we have large allocations, spanning more than one segment, and
the internal segment references from lead to secondary are the
only thing keeping a segment alive, the implicit drop in
discard_unused_segments and orphan_all can cause a recursive call
to discard_unused_segments, which in turn can lead to vector
corruption/crash, or even double free of segment (iterator confusion).

Need to separate the modification of the vector (_segments) from
actual releasing of objects. Using temporaries is the easiest
solution.

To further reduce recursion, we can also do an early clear of
segment dependencies in callbacks from segment release (cf release).

Closes scylladb/scylladb#25719

(cherry picked from commit cc9eb321a1)

Closes scylladb/scylladb#25755
2025-08-30 18:51:35 +03:00
Avi Kivity
1ae593da2e Merge 'token_range_vector: fragment' from Avi Kivity
token_range_vector is a sequence of intervals of tokens. It is used
to describe vnodes or token ranges owned by shards.

Since tokens are bloated (16 bytes instead of 8), and intervals are bloated
(40 byte of overhead instead of 8), and since we have plenty of token ranges,
such vectors can exceed our allocation unit of 128 kB and cause allocation stalls.

This series fixes that by first generalizing some helpers and then changing
token_range_vector to use chunked_vector.

Although this touches IDL, there is no compatibility problem since the encoding
for vector and chunked_vector are identical.

There is no performance concern since token_range_vector is never used on
any hot path (hot paths always contain a partition key).

Fixes #3335.
Fixes #24115.

Fixes #24156

Closes scylladb/scylladb#25659

* github.com:scylladb/scylladb:
  dht: fragment token_range_vector
  partition_range_compat: generalize wrap/unwrap helpers
  utils: chunked_vector: add swap() method
  utils: chunked_vector: add range insert() overloads
2025-08-26 22:43:08 +03:00
Taras Veretilnyk
c272dc7746 keys: from_nodetool_style_string don't split single partition keys
Users with single-column partition keys that contain colon characters
were unable to use certain REST APIs and 'nodetool' commands, because the
API split key by colon regardless of the partition key schema.

Affected commands:
- 'nodetool getendpoints'
- 'nodetool getsstables'
Affected endpoints:
- '/column_family/sstables/by_key'
- '/storage_service/natural_endpoints'

Refs: #16596 - This does not fully fix the issue, as users with compound
keys will face the issue if any column of the partition key contains
a colon character.

Closes scylladb/scylladb#24829

Closes scylladb/scylladb#25564
2025-08-26 10:31:54 +03:00
Avi Kivity
6171da6fbc utils: chunked_vector: add swap() method
Following std::vector(), we implement swap(). It's a simple matter
of swapping all the contents.

A unit test is added.

(cherry picked from commit 13a75ff835)
2025-08-25 12:44:13 +03:00
Avi Kivity
faaec66be7 utils: chunked_vector: add range insert() overloads
Inserts an iterator range at some position.

Again we insert the range at the end and use std::rotate() to
move the newly inserted elements into place, forgoing possible
optimizations.

Unit tests are added.

(cherry picked from commit 24e0d17def)
2025-08-25 12:44:13 +03:00
Dawid Mędrek
99b65be52e main: Log RF-rack-invalid keyspaces at startup
When the configuration option `rf_rack_valid_keyspaces` is enabled and there
is an RF-rack-invalid keyspace, starting a node fails. However, when the
configuration option is disabled, but there still is a keyspace that violates
the condition, we'd like Scylla to print a warning informing the user about
the fact. That's what happens in this commit.

We provide a validation test.

(cherry picked from commit 837d267cbf)
2025-08-22 14:31:13 +00:00
Dawid Mędrek
4df1d35375 cql3: Warn when creating RF-rack-invalid keyspace
Although RF-rack-valid keyspaces are not universally enforced
yet (they're governed by the configuration option
`rf_rack_valid_keyspaces`), we'd like to encourage the user to
abide by the restriction.

To that end, we're introducing a warning when creating or
altering a keyspace. If the configuration option is disabled,
but the user is trying to create an RF-rack-invalid keyspace,
they'll receive a warning.

We provide a validation test.

(cherry picked from commit 60ea22d887)
2025-08-22 14:31:13 +00:00
Pavel Emelyanov
dee53a0107 Merge '[Backport 2025.2] generic server: 2 step shutdown' from Scylladb[bot]
This PR implements solution proposed in scylladb/scylladb#24481

Instead of terminating connections immediately, the shutdown now proceeds in two stages: first closing the receive (input) side to stop new requests, then waiting for all active requests to complete before fully closing the connections.

The updated shutdown process is as follows:

1. Initial Shutdown Phase
   * Close the accept gate to block new incoming connections.
   * Abort all accept() calls.
   * For all active connections:
      * Close only the input side of the connection to prevent new requests.
      * Keep the output side open to allow responses to be sent.

2. Drain Phase
   * Wait for all in-progress requests to either complete or fail.

3. Final Shutdown Phase
   * Fully close all connections.

Fixes scylladb/scylladb#24481

- (cherry picked from commit 122e940872)

- (cherry picked from commit 3848d10a8d)

- (cherry picked from commit 3610cf0bfd)

- (cherry picked from commit 27b3d5b415)

- (cherry picked from commit 061089389c)

- (cherry picked from commit 7334bf36a4)

- (cherry picked from commit ea311be12b)

- (cherry picked from commit 4f63e1df58)

Parent PR: #24499

Closes scylladb/scylladb#25518

* github.com:scylladb/scylladb:
  test: Set `request_timeout_on_shutdown_in_seconds` to `request_timeout_in_ms`,  decrease request timeout.
  generic_server: Two-step connection shutdown.
  transport: consmetic change, remove extra blanks.
  generic_server: replace empty destructor with `= default`
  generic_server: refactor connection::shutdown to use `shutdown_input` and `shutdown_output`
  generic_server: add `shutdown_input` and `shutdown_output` functions to `connection` class.
  test: Add test for query execution during CQL server shutdown
2025-08-19 17:11:22 +03:00
Wojciech Mitros
6f7f639f54 test: run mv tests depending on metrics on a standalone instance
The test_base_partition_deletion_with_metrics test case (and the batch
variant) uses the metric of view updates done during its runtime to check
if we didn't perform too many of them. The test runs in the cqlpy suite,
which  runs all test cases sequentially on one Scylla instance. Because
of this, if another test case starts a process which generates view
updates and doesn't wait for it to finish before it exists, we may
observe too many view updates in test_base_partition_deletion_with_metrics
and fail the test.
In all test cases we make sure that all tables that were created
during the test are dropped at the end. However, that doesn't
stop the view building process immediately, so the issue can happen
even if we drop the view. I confirmed it by adding a test just before
test_base_partition_deletion_with_metrics which builds a big
materialized view and drops it at the end - the metrics check still failed.

The issue could be caused by any of the existing test cases where we create
a view and don't wait for it to be built. Note that even if we start adding
rows after creating the view, some of them may still be included in the view
building, as the view building process is started asynchronously. In such
a scenario, the view building also doesn't cause any issues with the data in
these tests - writes performed after view creation generate view updates
synchronously when they're local (and we're running a single Scylla server),
the corresponding view udpates generated during view building are redundant.

Because we have many test cases which could be causing this issue, instead
of waiting for the view building to finish in every single one of them, we
move the susceptible test cases to be run on separate Scylla instances, in
the "cluster" suite. There, no other test cases will influence the results.

Fixes https://github.com/scylladb/scylladb/issues/20379

Closes scylladb/scylladb#25209

(cherry picked from commit 2ece08ba43)

Closes scylladb/scylladb#25503
2025-08-19 17:10:58 +03:00
Pavel Emelyanov
39a85df231 Merge '[Backport 2025.2] test: test_mv_backlog: fix to consider internal writes' from Scylladb[bot]
The PR fixes a test flakiness issue in test_mv_backlog related to reading metrics.

The first commit fixes a more general issue in the ScyllaMetrics helper class where it doesn't return the value of all matching lines when a specific shard is requested, but it breaks after the first match.

The second commit fixes a test issue where it expects exactly one write to be throttled, not taking into account other internal writes that may be executed during this time.

Fixes https://github.com/scylladb/scylladb/issues/23139

backport to improve CI stability - test only change

- (cherry picked from commit 5c28cffdb4)

- (cherry picked from commit 276a09ac6e)

Parent PR: #25279

Closes scylladb/scylladb#25474

* github.com:scylladb/scylladb:
  test: test_mv_backlog: fix to consider internal writes
  test/pylib/rest_client: fix ScyllaMetrics filtering
2025-08-19 17:10:39 +03:00
Ferenc Szili
a0a346496e test: remove test_tombstone_gc_disabled_on_pending_replica
The test test_tombstone_gc_disabled_on_pending_replica was added when
we fixed (#20788) the potential problem with data resurrection during
file based streaming. The issue was occurring only in Enterprise, but
we added the fix in OSS to limit code divergence. This test was added
together with the fix in OSS with the idea to guard this change in OSS.
The real reproducer and test for this fix was added later, after the
fix was ported into Enterprise.
It is in: test/cluster/test_resurrection.py

Since Enterprise has been merged into OSS, there is no more need to
keep the test test_tombstone_gc_disabled_on_pending_replica. Also,
it is flaky with very low probability of failure, making it difficult
to investigate the cause of failure.

Fixes: #22182

Refs: scylladb/scylladb#25448

Closes scylladb/scylladb#25134

(cherry picked from commit 7ce96345bf)

Closes scylladb/scylladb#25572
2025-08-19 16:02:42 +03:00
Patryk Jędrzejczak
3113968380 test: test_maintenance_socket: use cluster_con for driver sessions
The test creates all driver sessions by itself. As a consequence, all
sessions use the default request timeout of 10s. This can be too low for
the debug mode, as observed in scylladb/scylla-enterprise#5601.

In this commit, we change the test to use `cluster_con`, so that the
sessions have the request timeout set to 200s from now on.

Fixes scylladb/scylla-enterprise#5601

This commit changes only the test and is a CI stability improvement,
so it should be backported all the way to 2024.2. 2024.1 doesn't have
this test.

Closes scylladb/scylladb#25510

(cherry picked from commit 03cc34e3a0)

Closes scylladb/scylladb#25546
2025-08-18 16:43:31 +02:00
Sergey Zolotukhin
687439615f test: Set request_timeout_on_shutdown_in_seconds to request_timeout_in_ms,
decrease request timeout.

In debug mode, queries may sometimes take longer than the default 30 seconds.
To address this, the timeout value `request_timeout_on_shutdown_in_seconds`
during tests is aligned with other request timeouts.
Change request timeout for tests from 180s to 90s since we must keep the request
timeout during shutdown significantly lower than the graceful shutdown timeout(2m),
or else a request timeout would cause a graceful shutdown timeout and fail a test.

(cherry picked from commit 4f63e1df58)
2025-08-15 18:20:45 +02:00
Sergey Zolotukhin
44853b3bec generic_server: Two-step connection shutdown.
When shutting down in `generic_server`, connections are now closed in two steps.
First, only the RX (receive) side is shut down. Then, after all ongoing requests
are completed, or a timeout happened the connections are fully closed.

Fixes scylladb/scylladb#24481

(cherry picked from commit ea311be12b)
2025-08-15 18:20:42 +02:00
Abhinav Jha
a0161ef67a raft: replication test: change rpc_propose_conf_change test to SEASTAR_THREAD_TEST_CASE
RAFT_TEST_CASE macro creates 2 test cases, one with random 20% packet
loss named name_drops. The framework makes hard coded assumptions about
leader which doesn't hold well in case of packet losses.

This short term fix disables the packet drop variant of the specified test.
It should be safe to re-enable it once the whole framework is re-worked to
remove these hard coded assumptions.

This PR fixes a bug. Hence we need to backport it.

Fixes: scylladb/scylladb#23816

Closes scylladb/scylladb#25489

(cherry picked from commit a0ee5e4b85)

Closes scylladb/scylladb#25527
2025-08-15 13:27:52 +03:00
Sergey Zolotukhin
aa8913f317 test: Add test for query execution during CQL server shutdown
This test simulates a scenario where a query is being executed while
the query coordinator begins shutting down the CQL server and client
connections. The shutdown process should wait until the query execution
is either completed or timed out.

Test for scylladb/scylladb#24481

(cherry picked from commit 122e940872)
2025-08-14 13:22:04 +00:00
Michael Litvak
a114e95798 test: test_mv_backlog: fix to consider internal writes
The test executes a single write, fetching metrics before and after the
write, and expects the total throttled writes count to be increased
exactly by one.

However, other internal writes (compaction for example) may be executed
during this time and be throttled, causing the metrics to be increased
by more than expected.

To address this, we filter the metrics by the scheduling group label of
the user write, to filter out the compaction writes that run in the
compaction scheduling group.

Fixes scylladb/scylladb#23139

(cherry picked from commit 276a09ac6e)
2025-08-12 20:53:16 +03:00
Michael Litvak
5161342910 test/pylib/rest_client: fix ScyllaMetrics filtering
In the ScyllaMetrics `get` function, when requesting the value for a
specific shard, it is expected to return the sum of all values of
metrics for that shard that match the labels.

However, it would return the value of the first matching line it finds
instead of summing all matching lines.

For example, if we have two lines for one shard like:
some_metric{scheduling_group_name="compaction",shard="0"} 1
some_metric{scheduling_group_name="sl:default",shard="0"} 2

The result of this call would be 1 instead of 3:
get('some_metric', shard="0")

We fix this to sum all matching lines.

The filtering of lines by labels is fixed to allow specifying only some
of the labels. Previously, for the line to match the filter, either the
filter needs to be empty, or all the labels in the metric line had to be
specified in the filter parameter and match its value, which is
unexpected, and breaks when more labels are added.

We also simplify the function signature and the implementation - instead
of having the shard as a separate parameter, it can be specified as a
label, like any other label.

(cherry picked from commit 5c28cffdb4)
2025-08-12 20:53:16 +03:00
Szymon Malewski
3791a6a4c5 test/alternator: enable more relevant logs in CI.
This patch sets, for alternator test suite, all 'alternator-*' loggers and 'paxos' logger to trace level. This should significantly ease debugging of failed tests, while it has no effect on test time and increases log size only by 7%.
This affects running alternator tests only with `test.py`, not with `test/alternator/run`.

Closes #24645

Closes scylladb/scylladb#25327

(cherry picked from commit eb11485969)

Closes scylladb/scylladb#25382
2025-08-11 06:59:34 +03:00
Benny Halevy
da0f9608d8 scylla-sstable: print_query_results_json: continue loop if row is disengaged
Otherwise it is accessed right when exiting the if block.
Add a unit test reproducing the issue and validating the fix.

Fixes #25325

Signed-off-by: Benny Halevy <bhalevy@scylladb.com>

Closes scylladb/scylladb#25326

(cherry picked from commit 5e5e63af10)

Closes scylladb/scylladb#25378
2025-08-10 18:54:29 +03:00
Botond Dénes
d845de84aa Merge '[Backport 2025.2] truncate: change check for write during truncate into a log warning' from Scylladb[bot]
TRUNCATE TABLE performs a memtable flush and then discards the sstables of the table being truncated. It collects the highest replay position for both of these. When the highest replay position of the discarded sstables is higher than the highest replay position of the flushed memtable, that means that we have had writes during truncate which have been flushed to disk independently of the truncate process. We check for this and trigger an on_internal_error() which throws an exception, informing the user that writing data concurrently with TRUNCATE TABLE is not advised.

The problem with this is that truncate is also called from DROP KEYSPACE and DROP TABLE. These are raft operations and exceptions thrown by them are caught by the (...) exception handler in the raft applier fiber, which then exits leaving the node without the ability to execute subsequent raft commands.

This commit changes the on_internal_error() into a warning log entry. It also outputs to keyspace/table names, and the offending replay positions which caused the check to fail.

This PR also adds a test which validates that TRUNCATE works correctly with concurrent writes. More specifically, it checks that:
- all data written before TRUNCATE starts is deleted
- none of the data after TRUNCATE completes is deleted

Fixes: #25173
Fixes: #25013

Backport is needed in versions which check for truncate with concurrent writes using `on_internal_error()`: 2025.3 2025.2 2025.1

- (cherry picked from commit 268ec72dc9)

- (cherry picked from commit 33488ba943)

Parent PR: #25174

Closes scylladb/scylladb#25349

* github.com:scylladb/scylladb:
  truncate: add test for truncate with concurrent writes
  truncate: change check for write during truncate into a log warning
2025-08-08 11:44:41 +03:00
Botond Dénes
cccf726b54 Merge '[Backport 2025.2] test: introduce upgrade tests to test.py, add a SSTable dict compression upgrade test' from Michał Chojnowski
This PR adds an upgrade test for SSTable compression with shared dictionaries, and adds some bits to pylib and test.py to support that.

In the series, we:

1. Mount $XDG_CACHE_DIR into dbuild.
2. Add a pylib function which downloads and installs a released ScyllaDB package into a subdirectory of $XDG_CACHE_DIR/scylladb/test.py, and returns the path to bin/scylla.
3. Add new methods and params to the cluster manager, which let the test start nodes with historical Scylla executables, and switch executables during the test.
4. Add a test which uses the above to run an upgrade test between the released package and the current build.
5. Add --run-internet-dependent-tests to test.py which lets the user of test.py skip this test (and potentially other internet-dependent tests in the future).

(The patch modifying wait_for_cql_and_get_hosts is a part of the new test — the new test needs it to test how particular nodes in a mixed-version cluster react to some CQL queries.)

This is a follow-up to https://github.com/scylladb/scylladb/pull/23025, split into a separate PR because the potential addition of upgrade tests to test.py deserved a separate thread.

Needs backport to 2025.2, because that's where the tested feature is introduced.

Fixes https://github.com/scylladb/scylladb/issues/24110

- (cherry picked from commit 63218bb094)
- (cherry picked from commit cc7432888e)
- (cherry picked from commit 34098fbd1f)
- (cherry picked from commit 2ef0db0a6b)
- (cherry picked from commit 1ff7e09edc)
- (cherry picked from commit 5da19ff6a6)
- (cherry picked from commit d3cb873532)
- (cherry picked from commit dd878505ca)

Parent PR: https://github.com/scylladb/scylladb/pull/23538

Closes scylladb/scylladb#25158

* github.com:scylladb/scylladb:
  test: add test_sstable_compression_dictionaries_upgrade.py
  test.py: add --run-internet-dependent-tests
  pylib/manager_client: add server_switch_executable
  test/pylib: in add_server, give a way to specify the executable and version-specific config
  pylib: pass scylla_env environment variables to the topology suite
  test/pylib: add get_scylla_2025_1_executable()
  pylib/scylla_cluster: give a way to pass executable-specific options to nodes
  dbuild: mount "$XDG_CACHE_HOME/scylladb"
2025-08-07 06:26:25 +03:00
Nikos Dragazis
5ae00a3dab test: kmip: Fix segfault from premature destruction of port_promise
`kmip_test_helper()` is a utility function to spawn a dedicated PyKMIP
server for a particular Boost test case. The function runs the server as
an external process and uses a thread to parse the port from the
server's logs. The thread communicates the port to the main thread via
a promise.

The current implementation has a bug where the thread may set a value
to the promise after its destruction, causing a segfault. This happens
when the server does not start within 20 seconds, in which case the port
future throws and the stack unwinding machinery destroys the port
promise before the thread that writes to it.

Fix the bug by declaring the promise before the cleanup action.

The bug has been encountered in CI runs on slow machines, where the
PyKMIP server takes too long to create its internal tables (due to slow
fdatasync calls from SQLite). This patch does not improve CI stability -
it only ensures that the error condition is properly reflected in the
test output.

This patch is not a backport. The same bug has been fixed in master as
part of a larger rewrite of the `kmip_test_helper()` (see 722e2bce96).

Refs #24747, #24842.
Fixes #24574.

Signed-off-by: Nikos Dragazis <nikolaos.dragazis@scylladb.com>

Closes scylladb/scylladb#25029
2025-08-06 11:58:56 +03:00
Raphael S. Carvalho
be94db3ace replica: Fix take_storage_snapshot() running concurrently to merge completion
Some background:
When merge happens, a background fiber wakes up to merge compaction
groups of sibling tablets into main one. It cannot happen when
rebuilding the storage group list, since token metadata update is
not preemptable. So a storage group, post merge, has the main
compaction group and two other groups to be merged into the main.
When the merge happens, those two groups are empty and will be
freed.

Consider this scenario:
1) merge happens, from 2 to 1 tablet
2) produces a single storage group, containing main and two
other compaction groups to be merged into main.
3) take_storage_snapshot(), triggered by migration post merge,
gets a list of pointer to all compaction groups.
4) t__s__s() iterates first on main group, yields.
5) background fiber wakes up, moves the data into main
and frees the two groups
6) t__s__s() advances to other groups that are now freed,
since step 5.
7) segmentation fault

In addition to memory corruption, there's also a potential for
data to escape the iteration in take_storage_snapshot(), since
data can be moved across compaction groups in background, all
belonging to the same storage group. That could result in
data loss.

Readers should all operate on storage group level since it can
provide a view on all the data owned by a tablet replica.
The movement of sstable from group A to B is atomic, but
iteration first on A, then later on B, might miss data that
was moved from B to A, before the iteration reached B.
By switching to storage group in the interface that retrieves
groups by token range, we guarantee that all data of a given
replica can be found regardless of which compaction group they
sit on.

Fixes #23162.

Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>

Closes scylladb/scylladb#24058

(cherry picked from commit 28056344ba)

Closes scylladb/scylladb#25338
2025-08-06 09:41:56 +03:00
Botond Dénes
22942c0a85 Merge '[Backport 2025.2] Raft-based recovery procedure: simplify rolling restart with recovery_leader' from Scylladb[bot]
The following steps are performed in sequence as part of the
Raft-based recovery procedure:
- set `recovery_leader` to the host ID of the recovery leader in
  `scylla.yaml` on all live nodes,
- send the `SIGHUP` signal to all Scylla processes to reload the config,
- perform a rolling restart (with the recovery leader being restarted
  first).

These steps are not intuitive and more complicated than they could be.

In this PR, we simplify these steps. From now on, we will be able to
simply set `recovery_leader` on each node just before restarting it.

Apart from making necessary changes in the code, we also update all
tests of the Raft-based recovery procedure and the user-facing
documentation.

Fixes scylladb/scylladb#25015

The Raft-based procedure was added in 2025.2. This PR makes the
procedure simpler and less error-prone, so it should be backported
to 2025.2 and 2025.3.

- (cherry picked from commit ec69028907)

- (cherry picked from commit 445a15ff45)

- (cherry picked from commit 23f59483b6)

- (cherry picked from commit ba5b5c7d2f)

- (cherry picked from commit 9e45e1159b)

- (cherry picked from commit f408d1fa4f)

Parent PR: #25032

Closes scylladb/scylladb#25334

* github.com:scylladb/scylladb:
  docs: document the option to set recovery_leader later
  test: delay setting recovery_leader in the recovery procedure tests
  gossip: add recovery_leader to gossip_digest_syn
  db: system_keyspace: peers_table_read_fixup: remove rows with null host_id
  db/config, gms/gossiper: change recovery_leader to UUID
  db/config, utils: allow using UUID as a config option
2025-08-06 09:41:17 +03:00
Dawid Mędrek
8e96968fb7 test: Enable RF-rack-valid keyspaces in all Python suites
We're enabling the configuration option `rf_rack_valid_keyspaces`
in all Python test suites. All relevant tests have been adjusted
to work with it enabled.

That encompasses the following suites:

* alternator,
* broadcast_tables,
* cluster (already enabled in scylladb/scylladb@ee96f8dcfc),
* cql,
* cqlpy (already enabled in scylladb/scylladb@be0877ce69),
* nodetool,
* rest_api.

Two remaining suites that use tests written in Python, redis and scylla_gdb,
are not affected, at least not directly.

The redis suite requires creating an instance of Scylla manually, and the tests
don't do anything that could violate the restriction.

The scylla_gdb suite focuses on testing the capabilities of scylla-gdb.py, but
even then it reuses the `run` file from the cqlpy suite.

Fixes scylladb/scylladb#25126

Closes scylladb/scylladb#24617

(cherry picked from commit b41151ff1a)

Closes scylladb/scylladb#25230
2025-08-06 09:35:34 +03:00
Ferenc Szili
932223414b truncate: add test for truncate with concurrent writes
test_validate_truncate_with_concurrent_writes checks if truncate deletes
all the data written before the truncate starts, and does not delete any
data after truncate completes.

(cherry picked from commit 33488ba943)
2025-08-06 00:51:43 +00:00
Patryk Jędrzejczak
beb28a6155 test: delay setting recovery_leader in the recovery procedure tests
In the previous commit, we made it possible to set `recovery_leader`
on each node just before restarting it. Here, we change all the
tests of the Raft-based recovery procedure to use and test this option.

(cherry picked from commit 9e45e1159b)
2025-08-05 10:59:06 +00:00
Patryk Jędrzejczak
b79902baf8 gossip: add recovery_leader to gossip_digest_syn
In the new Raft-based recovery procedure, live nodes join the new
group 0 one by one during a rolling restart. There is a time window when
some of them are in the old group 0, while others are in the new group
0. This causes a group 0 mismatch in `gossiper::handle_syn_msg`. The
current solution for this problem is to ignore group 0 mismatches if
`recovery_leader` is set on the local node and to ask the administrator
to perform the rolling restart in the following way:
- set `recovery_leader` in `scylla.yaml` on all live nodes,
- send the `SIGHUP` signal to all Scylla processes to reload the config,
- proceed with the rolling restart.

This commit makes `gossiper::handle_syn_msg` ignore group 0 mismatches
when exactly one of the two gossiping nodes has `recovery_leader` set.
We achieve this by adding `recovery_leader` to `gossip_digest_syn`.
This change makes setting `recovery_leader` earlier on all nodes and
reloading the config unnecessary. From now on, the administrator can
simply restart each node with `recovery_leader` set.

However, note that nodes that join group 0 must have `recovery_leader`
set until all nodes join the new group 0. For example, assume that we
are in the middle of the rolling restart and one of the nodes in the new
group 0 crashes. It must be restarted with `recovery_leader` set, or
else it would reject `gossip_digest_syn` messages from nodes in the old
group 0. To avoid problems in such cases, we will continue to recommend
setting `recovery_leader` in `scylla.yaml` instead of passing it as
a command line argument.

(cherry picked from commit ba5b5c7d2f)
2025-08-05 10:59:06 +00:00
Nikos Dragazis
f53588813b test: Use in-memory SQLite for PyKMIP server
The PyKMIP server uses an SQLite database to store artifacts such as
encryption keys. By default, SQLite performs a full journal and data
flush to disk on every CREATE TABLE operation. Each operation triggers
three fdatasync(2) calls. If we multiply this by 16, that is the number
of tables created by the server, we get a significant number of file
syncs, which can last for several seconds on slow machines.

This behavior has led to CI stability issues from KMIP unit tests where
the server failed to complete its schema creation within the 20-second
timeout (observed on spider9 and spider11).

Fix this by configuring the server to use an in-memory SQLite.

Fixes #24842.

Signed-off-by: Nikos Dragazis <nikolaos.dragazis@scylladb.com>

Closes scylladb/scylladb#24995

(cherry picked from commit 2656fca504)

Closes scylladb/scylladb#25299
2025-08-02 17:13:13 +03:00
Piotr Dulikowski
c4b4db62e3 Merge '[Backport 2025.2] qos: don't populate effective service level cache until auth is migrated to raft' from Scylladb[bot]
Right now, service levels are migrated in one group0 command and auth is migrated in the next one. This has a bad effect on the group0 state reload logic - modifying service levels in group0 causes the effective service levels cache to be recalculated, and to do so we need to fetch information about all roles. If the reload happens after SL upgrade and before auth upgrade, the query for roles will be directed to the legacy auth tables in system_auth - and the query, being a potentially remote query, has a timeout. If the query times out, it will throw an exception which will break the group0 apply fiber and the node will need to be restarted to bring it back to work.

In order to solve this issue, make sure that the service level module does not start populating and using the service level cache until both service levels and auth are migrated to raft. This is achieved by adding the check both to the cache population logic and the effective service level getter - they now look at service level's accessor new method, `can_use_effective_service_level_cache` which takes a look at the auth version.

Fixes: scylladb/scylladb#24963

Should be backported to all versions which support upgrade to topology over raft - the issue described here may put the cluster into a state which is difficult to get out of (group0 apply fiber can break on multiple nodes, which necessitates their restart).

- (cherry picked from commit 2bb800c004)

- (cherry picked from commit 3a082d314c)

Parent PR: #25188

Closes scylladb/scylladb#25284

* github.com:scylladb/scylladb:
  test: sl: verify that legacy auth is not queried in sl to raft upgrade
  qos: don't populate effective service level cache until auth is migrated to raft
2025-08-01 17:15:25 +02:00
Piotr Dulikowski
d9075e6160 test: sl: verify that legacy auth is not queried in sl to raft upgrade
Adjust `test_service_levels_upgrade`: right before upgrade to topology
on raft, enable an error injection which triggers when the standard role
manager is about to query the legacy auth tables in the
system_auth keyspace. The preceding commit which fixes
scylladb/scylladb#24963 makes sure that the legacy tables are not
queried during upgrade to topology on raft, so the error injection does
not trigger and does not cause a problem; without that commit, the test
fails.

(cherry picked from commit 3a082d314c)
2025-07-31 15:13:24 +00:00
Piotr Dulikowski
618459125d qos: don't populate effective service level cache until auth is migrated to raft
Right now, service levels are migrated in one group0 command and auth
is migrated in the next one. This has a bad effect on the group0 state
reload logic - modifying service levels in group0 causes the effective
service levels cache to be recalculated, and to do so we need to fetch
information about all roles. If the reload happens after SL upgrade and
before auth upgrade, the query for roles will be directed to the legacy
auth tables in system_auth - and the query, being a potentially remote
query, has a timeout. If the query times out, it will throw
an exception which will break the group0 apply fiber and the node will
need to be restarted to bring it back to work.

In order to solve this issue, make sure that the service level module
does not start populating and using the service level cache until both
service levels and auth are migrated to raft. This is achieved by adding
the check both to the cache population logic and the effective service
level getter - they now look at service level's accessor new method,
`can_use_effective_service_level_cache` which takes a look at the auth
version.

Fixes: scylladb/scylladb#24963
(cherry picked from commit 2bb800c004)
2025-07-31 15:13:23 +00:00
Pavel Emelyanov
45101e072e Merge '[Backport 2025.2] transport: remove throwing protocol_exception on connection start' from Dario Mirovic
Note: The simplest approach to resolving `process_request_one` merge issues, since it has been refactored, was to include the three commits from before, and then the commits that are actually being backported.

`protocol_exception` is thrown in several places. This has become a performance issue, especially when starting/restarting a server. To alleviate this issue, throwing the exception has to be replaced with returning it as a result or an exceptional future.

This PR replaces throws in the `transport/server` module. This is achieved by using result_with_exception, and in some places, where suitable, just by creating and returning an exceptional future.

There are four commits in this PR. The first commit introduces tests in `test/cqlpy`. The second commit refactors transport server `handle_error` to not rethrow exceptions. The third commit refactors reusable buffer writer callbacks. The fourth commit replaces throwing `protocol_exception` to returning it.

Based on the comments on an issue linked in https://github.com/scylladb/scylladb/issues/24567, the main culprit from the side of protocol exceptions is the invalid protocol version one, so I tested that exception for performance.

In order to see if there is a measurable difference, a modified version of `test_protocol_version_mismatch` Python is used, with 100'000 runs across 10 processes (not threads, to avoid Python GIL). One test run consisted of 1 warm-up run and 5 measured runs. First test run has been executed on the current code, with throwing protocol exceptions. Second test urn has been executed on the new code, with returning protocol exceptions. The performance report is in https://github.com/scylladb/scylladb/pull/24738#issuecomment-3051611069. It shows ~10% gains in real, user, and sys time for this test.

Testing

Build: `release`

Test file: `test/cqlpy/test_protocol_exceptions.py`
Test name: `test_protocol_version_mismatch` (modified for mass connection requests)

Test arguments:
```
max_attempts=100'000
num_parallel=10
```

Throwing `protocol_exception` results:
```
real=1:26.97  user=10:00.27  sys=2:34.55  cpu=867%
real=1:26.95  user=9:57.10  sys=2:32.50  cpu=862%
real=1:26.93  user=9:56.54  sys=2:35.59  cpu=865%
real=1:26.96  user=9:54.95  sys=2:32.33  cpu=859%
real=1:26.96  user=9:53.39  sys=2:33.58  cpu=859%

real=1:26.95 user=9:56.85 sys=2:34.11 cpu=862%   # average
```

Returning `protocol_exception` as `result_with_exception` or an exceptional future:
```
real=1:18.46  user=9:12.21  sys=2:19.08  cpu=881%
real=1:18.44  user=9:04.03  sys=2:17.91  cpu=869%
real=1:18.47  user=9:12.94  sys=2:19.68  cpu=882%
real=1:18.49  user=9:13.60  sys=2:19.88  cpu=883%
real=1:18.48  user=9:11.76  sys=2:17.32  cpu=878%

real=1:18.47 user=9:10.91 sys=2:18.77 cpu=879%   # average
```

This PR replaced `transport/server` throws of `protocol_exception` with returns. There are a few other places where protocol exceptions are thrown, and there are many places where `invalid_request_exception` is thrown. That is out of scope of this single PR, so the PR just refs, and does not resolve issue #24567.

Refs: #24567

This PR improves performance in cases when protocol exceptions happen, for example during connection storms. It will require backporting.

* (cherry picked from commit 7aaeed012e)

* (cherry picked from commit 30d424e0d3)

* (cherry picked from commit 9f4344a435)

* (cherry picked from commit 5390f92afc)

* (cherry picked from commit 4a6f71df68)

Parent PR: #24738

Closes scylladb/scylladb#25239

* github.com:scylladb/scylladb:
  test/cqlpy: add cpp exception metric test conditions
  transport/server: replace protocol_exception throws with returns
  utils/reusable_buffer: accept non-throwing writer callbacks via result_with_exception
  transport/server: avoid exception-throw overhead in handle_error
  test/cqlpy: add protocol_exception tests
  transport: remove redundant references in process_request_one
  transport: fix the indentation in process_request_one
  transport: add futures in CQL server exception handling
2025-07-31 12:18:50 +03:00
Dario Mirovic
9708d9c4d7 test/cqlpy: add cpp exception metric test conditions
Tested code paths should not throw exceptions. `scylla_reactor_cpp_exceptions`
metric is used. This is a global metric. To address potential test flakiness,
each test runs multiple times:
- `run_count = 100`
- `cpp_exception_threshold = 10`

If a change in the code introduced an exception, expectation is that the number
of registered exceptions will be > `cpp_exception_threshold` in `run_count` runs.
In which case the test fails.

Fixes: #25272
(cherry picked from commit 4a6f71df68)
2025-07-30 21:54:47 +02:00
Dario Mirovic
a8d38882ff utils/reusable_buffer: accept non-throwing writer callbacks via result_with_exception
Make make_bytes_ostream and make_fragmented_temporary_buffer accept
writer callbacks that return utils::result_with_exception instead of
forcing them to throw on error. This lets callers propagate failures
by returning an error result rather than throwing an exception.

Introduce buffer_writer_for, bytes_ostream_writer, and fragmented_buffer_writer
concepts to simplify and document the template requirements on writer callbacks.

This patch does not modify the actual callbacks passed, except for the syntax
changes needed for successful compilation, without changing the logic.

Refs: #24567
Fixes: #25272
(cherry picked from commit 9f4344a435)
2025-07-30 21:54:41 +02:00
Dario Mirovic
57a32e50d3 test/cqlpy: add protocol_exception tests
Add a helper to fetch scylla_transport_cql_errors_total{type="protocol_error"} counter
from Scylla's metrics endpoint. These metrics are used to track protocol error
count before and after each test.

Add cql_with_protocol context manager utility for session creation with parameterized
protocol_version value. This is used for testing connection establishment with
different protocol versions, and proper disposal of successfully established sessions.

The tests cover two failure scenarios:
- Protocol version mismatch in test_protocol_version_mismatch which tests both supported
and unsupported protocol version
- Malformed frames via raw socket in _protocol_error_impl, used by several test functions,
and also test_no_protocol_exceptions test to assert that the error counters never decrease
during test execution, catching unintended metric resets

Refs: #24567
Fixes: #25272
(cherry picked from commit 7aaeed012e)
2025-07-30 21:54:27 +02:00
Pavel Emelyanov
95b906bea9 Merge '[Backport 2025.2] storage_service: cancel all write requests after stopping transports' from Scylladb[bot]
When a node shuts down, in storage service, after storage_proxy RPCs are stopped, some write handlers within storage_proxy may still be waiting for background writes to complete. These handlers hold appropriate ERMs to block schema changes before the write finishes. After the RPCs are stopped, these writes cannot receive the replies anymore.

If, at the same time, there are RPC commands executing `barrier_and_drain`, they may get stuck waiting for these ERM holders to finish, potentially blocking node shutdown until the writes time out.

This change introduces cancellation of all outstanding write handlers from storage_service after the storage proxy RPCs were stopped.

Fixes scylladb/scylladb#23665

Backport: since this fixes an issue that frequently causes issues in CI, backport to 2025.1, 2025.2, and 2025.3.

- (cherry picked from commit bc934827bc)

- (cherry picked from commit e0dc73f52a)

Parent PR: #24714

Closes scylladb/scylladb#25169

* github.com:scylladb/scylladb:
  storage_service: Cancel all write requests on storage_proxy shutdown
  test: Add test for unfinished writes during shutdown and topology change
2025-07-28 09:25:15 +03:00
Pavel Emelyanov
8622a07bdd Merge '[Backport 2025.2] streaming: Avoid deadlock by running view checks in a separate scheduling group' from Scylladb[bot]
This issue happens with removenode, when RBNO is disabled, so range
streamer is used.

The deadlock happens in a scenario like this:
1. Start 3 nodes: {A, B, C}, RF=2
2. Node A is lost
3. removenode A
4. Both B and C gain ownership of ranges.
5. Streaming sessions are started with crossed directions: B->C, C->B

Readers created by sender side exhaust streaming semaphore on B and C.
Receiver side attempts to obtain a permit indirectly by calling
check_needs_view_update_path(), which reads local tables. That read is
blocked and times-out, causing streaming to fail. The streaming writer
is already using a tracking-only permit.

Even if we didn't deadlock, and the streaming semaphore was simply exhausted
by other receiving sessions (via tracking-only permit), the query may still time-out due to starvation.

To avoid that, run the query under a different scheduling group, which
translates to the system semaphore instead of the maintenance
semaphore, to break the dependency. The gossip group was chosen
because it shouldn't be contended and this change should not interfere
with it much.

Fixes #24807
Fixes #24925

- (cherry picked from commit ee2fa58bd6)

- (cherry picked from commit dff2b01237)

Parent PR: #24929

Closes scylladb/scylladb#25055

* github.com:scylladb/scylladb:
  streaming: Avoid deadlock by running view checks in a separate scheduling group
  service: migration_manager: Run group0 barrier in gossip scheduling group
2025-07-28 09:24:53 +03:00
Tomasz Grabiec
3991e4de28 streaming: Avoid deadlock by running view checks in a separate scheduling group
This issue happens with removenode, when RBNO is disabled, so range
streamer is used.

The deadlock happens in a scenario like this:
1. Start 3 nodes: {A, B, C}, RF=2
2. Node A is lost
3. removenode A
4. Both B and C gain ownership of ranges.
5. Streaming sessions are started with crossed directions: B->C, C->B

Readers created by sender side exhaust streaming semaphore on B and C.
Receiver side attempts to obtain a permit indirectly by calling
check_needs_view_update_path(), which reads local tables. That read is
blocked and times-out, causing streaming to fail. The streaming writer
is already using a tracking-only permit.

To avoid that, run the query under a different scheduling group, which
translates to the system semaphore instead of the maintenance
semaphore, to break the dependency. The gossip group was chosen
because it shouldn't be contended and this change should not interfere
with it much.

Fixes: #24807
(cherry picked from commit dff2b01237)
2025-07-27 22:52:56 +02:00