PM78144: IBM HTTP SERVER LARGE LOGFORMATS CANNOT BE CORRECTLY LOGGED BY PIPED LOGGERS

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APAR status

  • Closed as program error.

Error description

  • In IBM HTTP Server (IHS) large logformats cannot be correctly
    logged by piped loggers.
    

Local fix

  • A workaround is to reduce the number of log strings used in the
    LogFormat directive in IBM HTTP Server.
    
    The customer can use multiple SHORT LogFormats with multiple
    CustomLog directives to write output to multiple log files,
    rather than using one LONG LogFormat for everything.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:  IBM HTTP Server users with access log       *
    *                  records longer than the Operating System's  *
    *                  PIPE_BUF who used piped loggers (for        *
    *                  example, rotatelogs)                        *
    ****************************************************************
    * PROBLEM DESCRIPTION: Long access log records are garbled     *
    *                      when                                    *
    *                      using piped loggers                     *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    When IBM HTTP Server writes long access log records to a pipe,
    the log is garbled.  POSIX only guarantees atomic writes for
    the first PIPE_BUF (4k on Linux) worth of data when writing to
    a Unix pipe.
    

Problem conclusion

  • mod_log_config is changed to support a new buffer size
    parameter
    on the BufferedLogs directive, coded like this:
    
    BufferedLogs on 40000     # 3rd arg is the buffer size in bytes
    
    When the access log is piped, such as with rotatelogs, and the
    specified buffer size is greater than PIPE_BUF, IBM HTTP
    Server will obtain a cross-process lock while writing the
    buffer to the pipe. This prevents other processes from writing
    to the pipe while the lock is held, and prevents the
    corruption of the log.
    

Temporary fix

Comments

APAR Information

  • APAR number

    PM78144

  • Reported component name

    IBM HTTP SERVER

  • Reported component ID

    5724J0801

  • Reported release

    700

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-11-29

  • Closed date

    2013-01-11

  • Last modified date

    2013-01-11

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

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

Fix information

  • Fixed component name

    IBM HTTP SERVER

  • Fixed component ID

    5724J0801

Applicable component levels

  • R61A PSY

       UP

  • R61H PSY

       UP

  • R61I PSY

       UP

  • R61P PSY

       UP

  • R61S PSY

       UP

  • R61W PSY

       UP

  • R61Z PSY

       UP

  • R700 PSY

       UP

  • R800 PSY

       UP

  • R850 PSY

       UP



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Document information


More support for:

IBM HTTP Server
Runtime

Software version:

7.0

Reference #:

PM78144

Modified date:

2013-01-11

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