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c4bf532d37
Here's another theoretical problem, that involves 3 sequential calls
to respectively removenode, force_removenode and some other operation.
Let's walk through them
First goes the removenode:
run_with_api_lock
_operation_in_progress = "removenode"
storage_service::remove_node
sleep in replicating_nodes.empty() loop
Now the force_removenode can run:
run_with_no_api_lock
storage_service::force_removenode
check _operation_in_progress (not empty)
_force_remove_completion = true
sleep in _operation_in_progress.empty loop
Now the 1st call wakes up and:
if _force_remove_completion == true
throw <some exception>
.finally() handler in run_with_api_lock
_operation_in_progress = <empty>
At this point some other operation may start. Say, drain:
run_with_api_lock
_operation_in_progress = "drain"
storage_service::drain
...
go to sleep somewhere
No let's go back to the 1st op that wakes up from its sleep.
The code it executes is
while (!ss._operation_in_progress.empty()) {
sleep_abortable()
}
and while the drain is running it will never exit.
However (! and this is the core of the race) should the drain
operation happen _before_ the force_removenode, another check
for _operation_in_progress would have made the latter exit with
the "Operation drain is in progress, try again" message.
Fix this inconsistency by making the check for current operation
every wake-up from the sleep_abortable.
Fixes #5591
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Scylla
Quick-start
To get the build going quickly, Scylla offers a frozen toolchain which would build and run Scylla using a pre-configured Docker image. Using the frozen toolchain will also isolate all of the installed dependencies in a Docker container. Assuming you have met the toolchain prerequisites, which is running Docker in user mode, building and running is as easy as:
$ ./tools/toolchain/dbuild ./configure.py
$ ./tools/toolchain/dbuild ninja build/release/scylla
$ ./tools/toolchain/dbuild ./build/release/scylla --developer-mode 1
Please see HACKING.md for detailed information on building and developing Scylla.
Note: GCC >= 8.1.1 is required to compile Scylla.
Running Scylla
- Run Scylla
./build/release/scylla
- run Scylla with one CPU and ./tmp as work directory
./build/release/scylla --workdir tmp --smp 1
- For more run options:
./build/release/scylla --help
Scylla APIs and compatibility
By default, Scylla is compatible with Apache Cassandra and its APIs - CQL and Thrift. There is also experimental support for the API of Amazon DynamoDB, but being experimental it needs to be explicitly enabled to be used. For more information on how to enable the experimental DynamoDB compatibility in Scylla, and the current limitations of this feature, see Alternator and Getting started with Alternator.
Documentation
Documentation can be found in ./docs and on the wiki. There is currently no clear definition of what goes where, so when looking for something be sure to check both. Seastar documentation can be found here. User documentation can be found here.
Building Fedora RPM
As a pre-requisite, you need to install Mock on your machine:
# Install mock:
sudo yum install mock
# Add user to the "mock" group:
usermod -a -G mock $USER && newgrp mock
Then, to build an RPM, run:
./dist/redhat/build_rpm.sh
The built RPM is stored in /var/lib/mock/<configuration>/result directory.
For example, on Fedora 21 mock reports the following:
INFO: Done(scylla-server-0.00-1.fc21.src.rpm) Config(default) 20 minutes 7 seconds
INFO: Results and/or logs in: /var/lib/mock/fedora-21-x86_64/result
Building Fedora-based Docker image
Build a Docker image with:
cd dist/docker
docker build -t <image-name> .
Run the image with:
docker run -p $(hostname -i):9042:9042 -i -t <image name>