PI65226: ZWAS HANG IN XMEM PROXY CODE READING PARAMETER FROM HTTP REQUEST BODY FOLLOWING MULTIPLE COMM FAILURES

Fixes are available

APAR status

Closed as program error.

Error description

abendec3 rc04130007 http timeout following a hang in xmem proxy
code in a servant process, reading a parameter from the http
request body. The hang can occur during a period where there are
multiple communication failures reading from clients, resulting
in async read failures. There is a timing window where a bad
return code from TCP/IP results in the destroy for the
connection at the same time the servant calls back into the
control process for more data. In this case the thread can hang
for good.
To establish if this problem applies, check for FFDCs
written for the following:
--
SRVE0133E: An error occurred while parsing parameters.
{0}java.io.IOException: Push service did not  complete
successfully; bytesRead=-1
--
there will be one or more cases where such an FFDC was
written. The problem is more likely to be exposed
if the frequency of these comm failures is high.
* for the hung thread (which depending on
configuration may result in HTTP timer excession and
and abendEC3 rc04130007) the top of the stack will
show
--
com.ibm.ws390.xmem.proxy.XMemProxySRCppUtilities.getNex
tHttpRequestBodyChunk(Native Method)
--

Local fix

Problem summary

****************************************************************
* USERS AFFECTED:  All users of IBM WebSphere Application      *
*                  Server V8.5 and V9.0                        *
****************************************************************
* PROBLEM DESCRIPTION: WebSphere Application Server for z/OS   *
*                      Servant thread hangs in                 *
*                      getNextHttpRequestBodyChunk, leading    *
*                      to                                      *
*                      an ABENDEC3/ABENDSEC3 when the HTTP     *
*                      dispatch time is exceeded.              *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************
When large requests are sent to the application server, a
portion of the request can be read into the Controller and
queued to a Servant before the entire request has been read.
The Servant will eventually call back into the Controller to
receive the rest of the request.  Sometimes, the connection to
the remote client unexpectedly breaks before the entire request
has been read, and normally an error is simply sent back to the
Servant indicating the problem.
However, there is a small timing window where if the Servant is
calling back into the Controller to read more of the request
just as the remote connection unexpectedly closes, the thread
in the Servant will hang forever, or until the HTTP dispatch
timeout leads to a Servant ABENDEC3.
The top of the Java stack of the thread that is hung will look
like this:
com.ibm.ws390.xmem.proxy.XMemProxySRCppUtilities.
getNextHttpRequestBodyChunk
com.ibm.ws390.xmem.proxy.channel.
XMemProxySRInboundHttpServiceContextImpl.
getNextHttpRequestBodyChunk
com.ibm.ws390.xmem.proxy.channel.
XMemProxySRInboundHttpServiceContextImpl.
getRequestBodyBuffer

Problem conclusion

Code was added to remove the timing window that led to the hang.

APAR PI65226 is currently targeted for inclusion in Fix Packs
8.5.5.12 and 9.0.0.3 of WebSphere Application Server.

Please refer to the Recommended Updates page for delivery
information:
http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980

In addition, please refer to URL:
http://www.ibm.com/support/docview.wss?rs=404&uid=swg27006970
for Fix Pack PTF information.

Temporary fix

Comments

APAR Information

APAR number
PI65226
Reported component name
WEBSPHERE FOR Z
Reported component ID
5655I3500
Reported release
850
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2016-07-01
Closed date
2017-02-21
Last modified date
2017-02-21

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
WEBSPHERE FOR Z
Fixed component ID
5655I3500

Applicable component levels

R850 PSY
UP

[{"Business Unit":{"code":"BU059","label":"IBM Software w\/o TPS"},"Product":{"code":"SS7K4U","label":"WebSphere Application Server for z\/OS"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"850","Line of Business":{"code":"LOB45","label":"Automation"}}]

Document Information

Modified date:
04 May 2022

Tips

PI65226: ZWAS HANG IN XMEM PROXY CODE READING PARAMETER FROM HTTP REQUEST BODY FOLLOWING MULTIPLE COMM FAILURES

Fixes are available

Subscribe

APAR status

Closed as program error.

Error description

Local fix

Problem summary

Problem conclusion

Temporary fix

Comments

APAR Information

APAR number

Reported component name

Reported component ID

Reported release

Status

PE

HIPER

Special Attention

Submitted date

Closed date

Last modified date

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

Fixed component ID

Applicable component levels

R850 PSY

Document Information

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