IT24426: "java.io.IOException: Too many open files" errors from MQ v7.5 queue manager when using MQ Telemetry

APAR status

• Closed as program error.

Error description

• FDCs are created with a probe ID XR013004, and an exception and
  stack like:
  
  |   |   Cause:1       :-  java.io.IOException: Too many open
  files
  |   |   Message:1     :-  Too many open files
  |   |   StackTrace:1  :-  java.io.IOException: Too many open
  files
  |   |   	at
  sun.nio.ch.ServerSocketChannelImpl.accept0(Native Method)
  |   |   	at
  sun.nio.ch.ServerSocketChannelImpl.accept(ServerSocketChannelImp
  l.java:191)
  |   |   	at
  com.ibm.mq.communications.NonBlockingListener.run(NonBlockingLis
  tener.java:263)
  |   |   	at java.lang.Thread.run(Thread.java:767)
  
  The content from these FDCs may be written to the mqxr.stderr
  file instead if the lack of available file handles means that
  new FDCs cannot be created.
  
  A list of open files for the server shows that many thousands of
  instances of the same file are being held open by the MQXR
  service JVM process - for instance an lsof output on Linux would
  show thousands of instances like:
  
  java       4792  mqm 3807r   REG              253,0     2518
  1443685 /opt/mqm/mqxr/SDK/WebContent/index.html
  java       4792  mqm 3808r   REG              253,0     2518
  1443685 /opt/mqm/mqxr/SDK/WebContent/index.html
  java       4792  mqm 3809r   REG              253,0     2518
  1443685 /opt/mqm/mqxr/SDK/WebContent/index.html
  java       4792  mqm 3810r   REG              253,0     2518
  1443685 /opt/mqm/mqxr/SDK/WebContent/index.html
  etc
  

Local fix

•  Restarting the XR service JVM would also have cleared this up -
  would have to be the entire server, not just the channel though
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  This issue affects users of IBM MQ Telemetry, with HTTP enabled
  on an MQTT channel, making HEAD requests on the hostname and
  port for that channel
  
  
  Platforms affected:
  Windows, Linux on x86-64, AIX
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  For each HEAD request received by the HTTP enabled MQTT channel,
  a file handle was being opened for each response created to
  return to the requesting client. This open file handle was never
  closed off.
  

Problem conclusion

• Any file handles opened as a result of creating the responses to
  HTTP HEAD requests are now closed, and there is no longer a
  buildup of open file handles.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v7.5       7.5.0.9
  v8.0       8.0.0.11
  v9.0 LTS   9.0.0.5
  v9.1 CD    9.1.1
  v9.1 LTS   9.1.0.1
  
  The latest available maintenance can be obtained from
  'WebSphere MQ Recommended Fixes'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006037
  
  If the maintenance level is not yet available information on
  its planned availability can be found in 'WebSphere MQ
  Planned Maintenance Release Dates'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006309
  ---------------------------------------------------------------
  

Temporary fix

Comments

APAR Information

• 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

  WMQ BASE MULTIP

• Fixed component ID

  5724H7241

Applicable component levels