Web Agent IPC Error

Document ID : KB000050269
Last Modified Date : 14/02/2018
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Description:

You may get this kind of error in the Web Agent log:

[14/Apr/2011:14:47:06] [Error] [CA WebAgent IPC] [10054][CSmSharedSegment::smalloc] Error allocating shared memory segment using key 0x6cc7b0a7 - File exists (17)
[14/Apr/2011:14:47:06] [Info] [CA WebAgent IPC] [10054] [CSmSem::SemRm] Removed semaphore 45285378
[14/Apr/2011:14:47:06] [Error] SiteMinder Agent
PID Cache error.
Failed to initialize PID Cache

Solution:

The following startup error messages:

"PID Cache error" is generated when web agent or LLAWP process is unable to create or attached to its required semaphores and shared memory segments. These are system resources required by the web agent to communicate between itself and LLAWP process to pass information.

"Error allocating shared memory segment using key" is a failure of this type can be created by the failure to create the segments or the segments being subsequently removed. As this is a startup issue it points to there being an issue with creation and the most likely reasons for this are:

  • Unavailable system resources (the system settings are too low)

  • Permission issues (old resources are left around with different permissions or another web agent created the system resources with the same key).

To try resolving the issue, you can try the following:

  1. Verify that shared memory and semaphores leftover from the web server that would be interfering:

    1. Shut down the web server

    2. Make sure the LLAWP process is shut down

    3. Check for shared memory and semaphores leftover from the web server using these commands:

      ipcs -s : list semaphores
      ipcs -m : list shared memory
      ipcrm -s : remove semaphores
      ipcrm -m : remove shared memory

      Then remove any shared memory or semaphores for this instance. Look in the Web Server error log for the semaphore and shared memory keys. Those are the ones which need to be removed.

    4. Start the web server.

  2. Check if the system has enough memory to handle the resource and session caches.

    1. If you have increased the session/resource cache size, then change them to default.

    2. If you are using the default values, then decrease to 0.

    3. Then restart the Web Server.

      Session and resource cache size parameters are:

      • MaxSessionCacheSize

      • MaxResourceCacheSize

The idea behind decreasing those values to 0 is to check whether your system has enough memory or not. There might be a loss of performance while those values are at 0, because there will be no caching. However if this issue disappears, then it means that you should add some memory to the system, or reduce the cache size to a lower level if adding memory isn't possible.