How to increase the number of semaphores

Solution Verified - Updated -

Issue

  • Need to increase semaphore array limits for Apache httpd

  • Need to increase maximum number of semaphore sets for a 3rd-party application

  • IBM DB2 database instances goes down with error "Requesting too many semaphores"

  • A Red Hat Enterprise Linux Server running a large program, such as a database crashes after about a day or so of running. Using the 'ipcs' command it was determined that the server crashes once 100 out of 128 semaphores have been used.

    [root@rhel6 ~]# ipcs -s
    
    ------ Semaphore Arrays --------
    key        semid      owner      perms      nsems     
    0x00000000 0          root       600        1         
    0x00000000 65537      root       600        1         
    0xdd3adabd 131074     user       600        1     
    

Environment

  • Red Hat Enterprise Linux 4
  • Red Hat Enterprise Linux 5
  • Red Hat Enterprise Linux 6
  • Red Hat Enterprise Linux 7

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