APAR status
Closed as program error.
Error description
After FixPack 16.0.0.3 which added Asynchronous TCP/IP Sockets I/O for Liberty on z/OS, a loop in native routine aio_exit_routine in mvs_aio_services.mc in load module bbgzsafm running under an SRB. This causes the system to be unresponsive by monopolizing each CPU. Once all Processors are looping you cannot stop or cancel the Liberty Server. This new function must be enabled with a RACF profile specific to the new function and the Angel Process must also be running. Reference link: https://ibm.biz/BdssKy You may see recursieve entries in the SYSTRACE output: 0001-00BC 00000000 SSRV 120 81309210 00000000 0000261A ...... .....D18C67AA TimerDIE There is a circumvention. The code that causes this problem is in a timeout routine. If you disable the timeout routine this problem won't occur. To disable related timeout routine set the following property in the bootstrap.properties: com.ibm.io.async.AIOHandlerCompletionTimeout=0
Local fix
The code that causes this problem is in a timeout routine. If you disable the timeout routine this problem won't occur. To disable related timeout routine set the following property in the bootstrap.properties: com.ibm.io.async.AIOHandlerCompletionTimeout=0
Problem summary
**************************************************************** * USERS AFFECTED: All users of IBM WebSphere Application * * Server Liberty for z/OS * **************************************************************** * PROBLEM DESCRIPTION: Loop in routine aio_exit_routine in * * mvs_aio_services.mc in bbgzsafm running * * under an SRB. * **************************************************************** * RECOMMENDATION: * **************************************************************** A timeout routine that processes stack elements had incorrect logic which lead to a circular stack. The circular stack caused the loop while running under an SRB. This lead to the server and the system becoming unresponsive.
Problem conclusion
Code has been modified in the SRB related routines to clear pointer values after a successful removal of a stack element. This will help prevent a circular stack. Also, the logic within the timeout routine has been corrected to prevent chaining errors. The fix for this APAR is currently targeted for inclusion in fix pack 17.0.0.1. Please refer to the Recommended Updates page for delivery information: http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980
Temporary fix
The Asynchronous I/O Feature (AsyncIO) is disabled by default. It is enabled by granting read access for the server's user ID to the specific SAF profile named BBG.AUTHMOD.BBGZSAFM.ZOSAIO and having an Angel Process active for the Liberty Server. There are 2 ways to disable AsyncIO: 1) remove the read access from the SAF profile named BBG.AUTHMOD.BBGZSAFM.ZOSAIO; OR 2) add the following property to the bootstrap.properties file: com.ibm.ws.tcpchannel.useZosAio=false It is possible to avoid this problem completely while still continuing to use the Asynchronous I/O feature by setting the following property in bootstrap.properties: com.ibm.io.async.AIOHandlerCompletionTimeout=0 The above property allows the Asynchronous I/O feature to be used but bypasses the specific code path that leads to the problem.
Comments
APAR Information
APAR number
PI72065
Reported component name
LIBERTY PROF -
Reported component ID
5655W6514
Reported release
CD0
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2016-11-09
Closed date
2017-01-03
Last modified date
2017-01-03
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
LIBERTY PROF -
Fixed component ID
5655W6514
Applicable component levels
RCD0 PSY
UP
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Document Information
Modified date:
14 December 2020