Vladimir Ozerov created IGNITE-4766:
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Summary: Relax worker thread wakeup logic in StipedExecutor
Key: IGNITE-4766
URL: https://issues.apache.org/jira/browse/IGNITE-4766
Project: Ignite
Issue Type: Task
Components: general
Affects Versions: 1.0
Reporter: Vladimir Ozerov
Assignee: Vladimir Ozerov
Fix For: 2.0
*Problem*
Worker threads in {{StripedExecutor}} have {{parked}} state flag. When set to
{{true}} NIO threads will call {{LockSupport.unpark}} after submitting new task
to a queue.
The problem is that this flag is only changed by worker thread. Thus, if NIO
worker submitted a new task and called {{unpark}}, worker will clean up
{{parked}} state only after real wake up what may take microseconds. All
subsequent submits from NIO thread occurred during this time will also invoke
{{unpark}} thus generating high contention on the underlying OS primitives.
Namely, condition variables which ultimately delegates to {{futex}} on Linux.
*Solution*
NIO threads must be able to clear {{parked}} state as well. Some CAS magic will
be required there. This way we will minimize number of {{unapark}} calls.
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