PM90528: __msgrcv_timed ASYNCIO HTTP SERVER HANG

A fix is available

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • Customer is running HTTP server for z/OS. Every once
    in a while, the server stops responding to new requests.  The
    server process issues an asyncio request with a message queue
    for notification.  It then uses the __msgrcv_timed C function to
    poll for a message upon asyncio completion.  The __msgrcv_timed
    function results in a call to BPX1QRC (msgrcv), which enters a
    timed wait for messages to be sent.  A timing window exists
    where a message could be sent at the same time we've timed out
    waiting for messages.  The msgrcv code returns to the
    __msgrcv_timed C function with both a message and an indication
    that the timer popped.  This leads to the C function returning
    to the HTTP server that no message was received.  Thus, the
    server task remains hung.
    

Local fix

  • N/A
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: Users of z/OS C runtime functions            *
    *                 __msgrcv_timed() or __semop_timed()          *
    ****************************************************************
    * PROBLEM DESCRIPTION: C/RTL functions __msgrcv_timed() and    *
    *                      __semop_timed() might fail with EAGAIN  *
    *                      errno, when function was actually       *
    *                      successful.                             *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    See problem description.
    

Problem conclusion

  • The code was changed to fix the problem.
    

Temporary fix

  • *********
    * HIPER *
    *********
    Please apply ++APAR.
    

Comments

APAR Information

  • APAR number

    PM90528

  • Reported component name

    LE FOR MVS & VM

  • Reported component ID

    568819801

  • Reported release

    780

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2013-06-06

  • Closed date

    2013-08-15

  • Last modified date

    2013-09-03

  • APAR is sysrouted FROM one or more of the following:

    OA42486

  • APAR is sysrouted TO one or more of the following:

    UK96731 UK96732 UK96733

Modules/Macros

  •    CELHXFR4 CELQXFR4 EDC40358
    

Fix information

  • Fixed component name

    LE C LIBRARY

  • Fixed component ID

    568819805

Applicable component levels

  • R770 PSY UK96731

       UP13/08/28 P F308

  • R780 PSY UK96732

       UP13/08/28 P F308

  • R790 PSY UK96733

       UP13/08/28 P F308

Fix is available

  • Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.



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Document information


More support for:

z/OS XL C/C++
Runtime

Software version:

780

Operating system(s):

MVS, z/OS

Reference #:

PM90528

Modified date:

2013-09-03

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