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Mysql Server stuck with a long semaphore wait

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  • Mysql Server stuck with a long semaphore wait

    Today my server become unresponsive due to a long semaphore wait. From slow query logs i can see that commit, rollback and select(which usually takes 0.1sec) took abnormally large amount of time i.e more than 10sec max 5min

    Im running Percona 5.5.32 x64

    InnoDB: Warning: a long semaphore wait:
    --Thread 1327466816 has waited at buf0flu.c line 1353 for 241.00 seconds the semaphore:
    S-lock on RW-latch at 0x2ab01b59f1b0 '&block->lock'
    a writer (thread id 1339287872) has reserved it in mode exclusive
    number of readers 0, waiters flag 1, lock_word: 0
    Last time read locked in file buf0flu.c line 1336
    Last time write locked in file /mnt/workspace/percona-server-5.5-rpms/label_exp/centos5-64/target/BUILD/Percona-Server-5.5.32-rel31.0/storage/innobase/btr/btr0cur.c lin
    e 306
    InnoDB: ###### Starts InnoDB Monitor for 30 secs to print diagnostic info:
    InnoDB: Pending preads 0, pwrites 0

    =====================================
    140405 23:21:51 INNODB MONITOR OUTPUT
    =====================================
    Per second averages calculated from the last 26 seconds



    mysql> show global variables like '%adaptive_hash_index%';
    +---------------------------------------+-------+
    | Variable_name | Value |
    +---------------------------------------+-------+
    | innodb_adaptive_hash_index | ON |
    | innodb_adaptive_hash_index_partitions | 1 |
    +---------------------------------------+-------+


    Please help

  • #2
    Hi, It was reported as a bug in mysql at "http://bugs.mysql.com/bug.php?id=48050". The triage shows that it has been taken as a feature request.

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