A range is diveded into N sub ranges so that each sub range contains 100
partitions. So N depends on the number of partitions in that range. N
can grow unbounded and the memory usage of vector to hold these sub
ranges can go unbouded.
Limit the max number of sub ranges a range can divided into.
The downside is that the limited sub range will make we include more
partitions in the checksum.
Fixes#1917
Use the new seastar's metrics_registration framework:
- Change the registration syntax.
- Add a long description for each counter.
Signed-off-by: Vlad Zolotarov <vladz@cloudius-systems.com>
Instead of putting all statistics under the same "storage_proxy" category
separate them into 2 groups according to where the corresponding counters
are updated:
- "storage_proxy_replica"
- "storage_proxy_coordinator"
Fixes#1763
Signed-off-by: Vlad Zolotarov <vladz@cloudius-systems.com>
When requests hit the commitlog, each of them will be assigned a replay
position, which we expect to be ordered. If reorders happen, the request
will be discarded and re-applied. Although this is supposed to be rare,
it does increase our latencies, specially when big requests are
involved. Processing big requests is expensive and if we have to do it
twice that adds to the cost.
The commitlog is supposed to issue replay positions in order, and it
coudl be that the code that adds them to the memtables will reorder
them. However, there is one instance in which the commitlog will not
keep its side of the bargain.
That happens when the reserve is exhausted, and we are allocating a
segment directly at the same time the reserve is being replenished. The
following sequence of events with its deferring points will ilustrate
it:
on_timer:
return this->allocate_segment(false). // defer here // then([this](sseg_ptr s) {
At this point, the segment id is already allocated.
new_segment():
if (_reserve_segments.empty()) {
[ ... ]
return allocate_segment(true).then ...
At this point, we have a new segment that has an id that is higher than
the previous id allocated.
Then we resume the execution from the deferring point in on_timer():
i = _reserve_segments.emplace(i, std::move(s));
The next time we need to allocate a segment, we'll pick it from the
reserve. But the segment in the reserve has an id that is lower than the
id that we have already used.
Reorders are bad, but this one is particularly bad: because the reorder
happens with the segment id side of the replay position, that means that
every request that falls into that segment will have to be reinserted.
This bug can be a bit tricky to reproduce. To make it more common, we
can artificially add a sleep() fiber after the allocate_segment(false)
in on_timer(). If we do that, we'll see a sea of reinsertions going on
in the logs (if dblog is set to debug).
Applying this patch (keeping the sleep) will make them all disappear.
We do this by rewriting the reserve logic, so that the segments always
come from the reserve. If we draw from a single pool all the time, there
is no chance of reordering happening. To make that more amenable, we'll
have the reserve filler always running in the background and take it out
of the timer code.
Signed-off-by: Glauber Costa <glauber@scylladb.com>
Message-Id: <49eb7edfcafaef7f1fdceb270639a9a8b50cfce7.1480531446.git.glauber@scylladb.com>
The information (last compacted keys) is lost after node is restarted
or schema is updated, which causes strategy to be rebuilt.
We need it for strategy to guarantee uniform distribution of token
range across sstables, or we could end up with 1 sstable of level L
overlapping with lots of sstables of level L+1, and that results in
a compaction of undesired length.
That information can be generated from scratch by getting last key
of newest sstable in each level > 0.
Fixes#1906.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Message-Id: <35ebd15977d5a8418239febb160c796cdc0e98fa.1480533805.git.raphaelsc@scylladb.com>
Streaming memtable have a delayed mode where many flushes are coalesced
together into one, with the actual flush happening later and propagated
to all the previous waiters.
However, the timer that triggers the actual flush was not using the
newly introduced flush infrastructure. This was a minor problem because
those flushes wouldn't try to take the semaphore, and so we could have
many flushes going on at the same time.
What was a potential performance issue became a correctness issue when
we moved the reversal of the dirty memory accounting out of
revert_potentially_cleaned_up_memory() into remove_from_flush_manager().
Since the latter is only called through the flush infrastructure, it
simply wasn't called. So the deferral of the reversal exposed this bug.
Signed-off-by: Glauber Costa <glauber@scylladb.com>
Message-Id: <0d5755375bc27524b8cfb9970c76d492b14d9eea.1480522742.git.glauber@scylladb.com>
This fix splits build_ami.sh --repo to three different options:
--repo-for-install is for Scylla package installation, only valid
during AMI construction.
--repo-for-update will be stored at /etc/yum.repos.d/scylla.repo, to
receive update package on AMI.
--repo is both, for installation and update.
Fixes#1872
Signed-off-by: Takuya ASADA <syuu@scylladb.com>
Message-Id: <1480438858-6007-1-git-send-email-syuu@scylladb.com>
"The goal of this series is to prevent unbounded memory use
in cases when requests are timing out. Write requests which timed
out may still occupy memory for a while because of local mutation
application. This memory is not accounted for and can build up.
First part of the fix changes local mutation application so that it times out
at about the same time as the request handler. Then the life
time of the request handler is extended to cover any background activity
of that request which hasn't timed out yet. This has two main effects:
(1) by timing out local writes we prevent build up of background activity
for timed out requests
(2) we ensure that memory used by background activity is not left
behind unaccounted for. This will prevent CQL server from admitting
more requests than memory usage limit allows.
Fixes #1756."
* tag 'tgrabiec/prevent-oom-on-timeouts-v5' of github.com:cloudius-systems/seastar-dev:
storage_proxy: Do not flood logs with timeout errors
database: Add counter for timed out writes
storage_proxy: Delay timeout response until background work ceases
storage_proxy: Propagate timeout to local writes
storage_proxy: Use shared ownership for abstract_write_response_handler
storage_proxy: Add counter for all alive write handlers
db: Allow writes to be timed out
db: Introduce counters for failed reads and writes
commitlog: Allow allocations to be timed out
utils/logalloc: Add ability to timeout run_when_memory_available() task
utils/flush_queue: Add ability to wait with a timeout
Timeout errors are flooding the log after local mutate can time
out. We don't log remote mutate timeouts, so for consistency we won't
log local ones as well.
There is a database counter for timed out writes which can be
consulted in order to check if they're occuring.
Perhaps this would be better solved by a generic log message
throttling/coalescing mechanism, but that's not ready yet.
Write requests which timed out may still occupy memory for a while due
to local write. It should time out soon as well but there is a time
window in which it has not yet. If we don't delay timeout response,
the request would be seen as not consuming any memory too early. This
in turn would cause the CQL server to allow more requests than we
want. In some cases causing OOM or exceeding memory limits and causing
excessive cache eviciton.
Fixes#1756.
Currently the counter uses _response_handlers.size(), but after later
patches we may have an active (timed out) write with no response
handler, so count live instances instead.
Problem will cause size tiered to return small jobs when there are
more than max_threshold sstables of similar size. For example, if
max_threshold is 32, and there are 36 sstables of similar size,
strategy will only return 4 sstables to be compacted. That's because
we incorrectly create a new bucket when it meets the max threshold.
What we should do is to allow buckets to grow beyond max threshold
and trim them when selecting the most suitable one for compaction.
Important to mention that estimation for size tiered will now
work better when there are more than max_threshold sstables of
similar size.
Fixes#1901.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Message-Id: <080bad70d6cb86eaf52ac1bdd6765ac47aab5b03.1478316140.git.raphaelsc@scylladb.com>
This reverts commit 0e9b75d406.
commitlog_test fails with this:
Running 14 test cases...
ERROR 2016-11-28 20:48:00,565 [shard 0] commitlog - Segment reserve is full! Ignoring and trying to continue, but shouldn't happen
ERROR 2016-11-28 20:48:00,578 [shard 0] commitlog - Segment reserve is full! Ignoring and trying to continue, but shouldn't happen
ERROR 2016-11-28 20:48:10,591 [shard 0] commitlog - Segment reserve is full! Ignoring and trying to continue, but shouldn't happen
ERROR 2016-11-28 20:48:20,601 [shard 0] commitlog - Segment reserve is full! Ignoring and trying to continue, but shouldn't happen
tests/commitlog_test.cc(203): fatal error in "test_commitlog_discard_completed_segments": critical check dn <= nn failed
ERROR 2016-11-28 20:48:20,645 [shard 0] commitlog - Segment reserve is full! Ignoring and trying to continue, but shouldn't happen
ERROR 2016-11-28 20:48:20,837 [shard 0] commitlog - Segment reserve is full! Ignoring and trying to continue, but shouldn't happen
WARN 2016-11-28 20:48:20,838 [shard 0] commitlog - Exception in segment reservation: std::system_error (error system:2, No such file or directory)
ERROR 2016-11-28 20:48:20,952 [shard 0] commitlog - Segment reserve is full! Ignoring and trying to continue, but shouldn't happen
ERROR 2016-11-28 20:48:31,064 [shard 0] commitlog - Segment reserve is full! Ignoring and trying to continue, but shouldn't happen
ERROR 2016-11-28 20:48:31,083 [shard 0] commitlog - Segment reserve is full! Ignoring and trying to continue, but shouldn't happen
ERROR 2016-11-28 20:48:31,098 [shard 0] commitlog - Segment reserve is full! Ignoring and trying to continue, but shouldn't happen
ERROR 2016-11-28 20:48:31,111 [shard 0] commitlog - Segment reserve is full! Ignoring and trying to continue, but shouldn't happen
ERROR 2016-11-28 20:48:31,113 [shard 0] commitlog - Segment reserve is full! Ignoring and trying to continue, but shouldn't happen
WARN 2016-11-28 20:48:31,116 [shard 0] commitlog - Could not allocate 16388 k bytes output buffer (16388 k required)
*** 1 failure detected in test suite "tests/commitlog_test.cc"
WARN 2016-11-28 20:48:31,117 [shard 0] commitlog - Exception in segment reservation: std::system_error (error system:2, No such file or directory)
New sstables are loaded and added in parallel, meaning that scylla can
potentially return stale data if a new sstable containing a tombstone
wasn't loaded yet. Compaction should also not run until all new sstables
are added for similar reasons.
Fix is about separating blocking and non-blocking steps to allow
atomic add of multiple new sstables.
Fixes#1368.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Message-Id: <14283b8a4a69127071d1fabef320a93c91817ec2.1480356073.git.raphaelsc@scylladb.com>
When requests hit the commitlog, each of them will be assigned a replay
position, which we expect to be ordered. If reorders happen, the request
will be discarded and re-applied. Although this is supposed to be rare,
it does increase our latencies, specially when big requests are
involved. Processing big requests is expensive and if we have to do it
twice that adds to the cost.
The commitlog is supposed to issue replay positions in order, and it
coudl be that the code that adds them to the memtables will reorder
them. However, there is one instance in which the commitlog will not
keep its side of the bargain.
That happens when the reserve is exhausted, and we are allocating a
segment directly at the same time the reserve is being replenished. The
following sequence of events with its deferring points will ilustrate
it:
on_timer:
return this->allocate_segment(false). // defer here // then([this](sseg_ptr s) {
At this point, the segment id is already allocated.
new_segment():
if (_reserve_segments.empty()) {
[ ... ]
return allocate_segment(true).then ...
At this point, we have a new segment that has an id that is higher than
the previous id allocated.
Then we resume the execution from the deferring point in on_timer():
i = _reserve_segments.emplace(i, std::move(s));
The next time we need to allocate a segment, we'll pick it from the
reserve. But the segment in the reserve has an id that is lower than the
id that we have already used.
Reorders are bad, but this one is particularly bad: because the reorder
happens with the segment id side of the replay position, that means that
every request that falls into that segment will have to be reinserted.
This bug can be a bit tricky to reproduce. To make it more common, we
can artificially add a sleep() fiber after the allocate_segment(false)
in on_timer(). If we do that, we'll see a sea of reinsertions going on
in the logs (if dblog is set to debug).
Applying this patch (keeping the sleep) will make them all disappear.
We do this by rewriting the reserve logic, so that the segments always
come from the reserve. If we draw from a single pool all the time, there
is no chance of reordering happening. To make that more amenable, we'll
have the reserve filler always running in the background and take it out
of the timer code.
Signed-off-by: Glauber Costa <glauber@scylladb.com>
Message-Id: <2606b97df39997bcf3af84a23adf17e094ffb0b8.1480107174.git.glauber@scylladb.com>
"We currently write the size_estimates system table for every schema
on a periodic basis, currently set to 5 minutes, which can interfere
with an ongoing workload.
This patchset virtualizes it such that queries are intercepted and we
calculate the results on the fly, only for the ranges the caller is interested in.
Fixes#1616"
* 'virtual-estimates/v4' of github.com:duarten/scylla:
size_estimates_virtual_reader: Add unit test
db: Delete size_estimates_recorder
size_estimates: Add virtual reader
column_family: Add support for virtual readers
storage_service: get_local_tokens() returns a future
nonwrapping_range: Add slice() function
range: Find a sequence's lower and upper bounds
system_keyspace: Build mutations for size estimates
size_estimates: Store the token range as bytes
range_estimates: Add schema
murmur3_partitioner: Convert maximum_token to sstring
When we finish writing a memtable, we revert the dirty memory charges
immediately. When we do that, dirty memory will grow back to what it
was, and soon (we hope) will go down again when we release the requests
for real.
During that time, we may not accept new requests. Sealing can take a
long time, specially in the face of Linux issues like the ones we have
seen in the past. It also will take proportionally more time if the
SSTables end up being small, which is a possibility in some scenarios.
This patch changes the dirty_memory_manager so that the charges won't be
reverted right after we finish the flush. Rather, we will hold on to it,
and revert it right before we update the cache. We don't need to do it
for all classes of memtable writes, because after we finish flushing,
flush_one() will destroy the hashed element anyway.
Signed-off-by: Glauber Costa <glauber@scylladb.com>
Message-Id: <2d5a8f6ca57d5036f4850ac163557bca59b8063d.1480004384.git.glauber@scylladb.com>
GCC 5.3.1 was unable to convert bound to optional<bound>.
sstables/sstables.cc:2494:123: error: no matching function for call to
‘nonwrapping_range<dht::ring_position>::nonwrapping_range(dht::ring_position,
dht::ring_position)’
(dtr.right.exclusive ? dht::ring_position::starting_at :
dht::ring_position::ending_at)(std::move(t2)));
In file included from ./dht/i_partitioner.hh:52:0,
from ./query-request.hh:28,
from ./clustering_key_filter.hh:27,
from sstables/sstables.hh:35,
from sstables/sstables.cc:38:
./range.hh:441:14: note: candidate: nonwrapping_range<T>::nonwrapping_range(
const wrapping_range<U>&) [with T = dht::ring_position]
explicit nonwrapping_range(const wrapping_range<T>& r)
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Message-Id: <95bbf984cd73a61739c8da99cf6cd5e94f1d1457.1479954360.git.raphaelsc@scylladb.com>
Since not all distributions have a version of LZ4 with
LZ4_compress_default(), we use it conditionally.
This is specially important beginning with version 1.7.3 of LZ4,
which deprecates the LZ4_compress() function in favour of
LZ4_compress_default() and thus prevents Scylla from compiling
due to the deprecated warning.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
Message-Id: <20161124092339.23017-1-duarte@scylladb.com>
In Thrift, SliceRange defines a count that limits the number of cells
to return from that row (in CQL3 terms, it limits the number of rows
in that partition). While this limit is honored in the engine, the
Thrift layer also applies the same limit, which, while redundant in
most cases, is used to support the get_paged_slice verb.
Currently, the limit is not being reset per Thrift row (CQL3
partition), so in practice, instead of limiting the cells in a row,
we're limiting the rows we return as well. This patch fixes that by
ensuring the limit applies only within a row/partition.
Fixes#1882
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
Message-Id: <20161123220001.15496-1-duarte@scylladb.com>
