[jira] [Created] (IGNITE-8761) WAL fsync at rollover should be asynchronous in LOG_ONLY and BACKGROUND modes

["Ivan Rakov (JIRA)" <ji...@apache.org>]

Ivan Rakov created IGNITE-8761:
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             Summary: WAL fsync at rollover should be asynchronous in LOG_ONLY and BACKGROUND modes
                 Key: IGNITE-8761
                 URL: https://issues.apache.org/jira/browse/IGNITE-8761
             Project: Ignite
          Issue Type: Improvement
          Components: persistence
            Reporter: Ivan Rakov
             Fix For: 2.6


Transactions may periodically hang for a few seconds in LOG_ONLY or BACKGROUND persistent modes. Thread dumps show that threads are hanging on syncing previous WAL segment during rollover:
{noformat}
  java.lang.Thread.State: RUNNABLE
   at java.nio.MappedByteBuffer.force0(MappedByteBuffer.java:-1)
   at java.nio.MappedByteBuffer.force(MappedByteBuffer.java:203)
   at org.apache.ignite.internal.processors.cache.persistence.wal.FileWriteAheadLogManager$FileWriteHandle.close(FileWriteAheadLogManager.java:2843)
   at org.apache.ignite.internal.processors.cache.persistence.wal.FileWriteAheadLogManager$FileWriteHandle.access$600(FileWriteAheadLogManager.java:2483)
   at org.apache.ignite.internal.processors.cache.persistence.wal.FileWriteAheadLogManager.rollOver(FileWriteAheadLogManager.java:1094)
{noformat}
Waiting for this fsync is not necessary action to ensure crash recovery guarantees. Instead of this, we should just perform fsyncs asychronously and ensure that they are completed prior to next checkpoint start.



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