Fixes are available
18.0.0.2: WebSphere Application Server Liberty 18.0.0.2
18.0.0.3: WebSphere Application Server Liberty 18.0.0.3
18.0.0.4: WebSphere Application Server Liberty 18.0.0.4
19.0.0.1: WebSphere Application Server Liberty 19.0.0.1
19.0.0.2: WebSphere Application Server Liberty 19.0.0.2
19.0.0.3: WebSphere Application Server Liberty 19.0.0.3
19.0.0.4: WebSphere Application Server Liberty 19.0.0.4
19.0.0.5: WebSphere Application Server Liberty 19.0.0.5
19.0.0.6: WebSphere Application Server Liberty 19.0.0.6
19.0.0.7: WebSphere Application Server Liberty 19.0.0.7
19.0.0.8: WebSphere Application Server Liberty 19.0.0.8
19.0.0.9: WebSphere Application Server Liberty 19.0.0.9
19.0.0.10: WebSphere Application Server Liberty 19.0.0.10
19.0.0.11: WebSphere Application Server Liberty 19.0.0.11
19.0.0.12: WebSphere Application Server Liberty 19.0.0.12
20.0.0.1: WebSphere Application Server Liberty 20.0.0.1
20.0.0.2: WebSphere Application Server Liberty 20.0.0.2
20.0.0.3: WebSphere Application Server Liberty 20.0.0.3
20.0.0.4: WebSphere Application Server Liberty 20.0.0.4
20.0.0.5: WebSphere Application Server Liberty 20.0.0.5
20.0.0.6: WebSphere Application Server Liberty 20.0.0.6
20.0.0.7: WebSphere Application Server Liberty 20.0.0.7
20.0.0.8: WebSphere Application Server Liberty 20.0.0.8
20.0.0.9: WebSphere Application Server Liberty 20.0.0.9
20.0.0.10: WebSphere Application Server Liberty 20.0.0.10
20.0.0.11: WebSphere Application Server Liberty 20.0.0.11
20.0.0.12: WebSphere Application Server Liberty 20.0.0.12
21.0.0.3: WebSphere Application Server Liberty 21.0.0.3
21.0.0.4: WebSphere Application Server Liberty 21.0.0.4
21.0.0.5: WebSphere Application Server Liberty 21.0.0.5
21.0.0.6: WebSphere Application Server Liberty 21.0.0.6
21.0.0.7: WebSphere Application Server Liberty 21.0.0.7
21.0.0.8: WebSphere Application Server Liberty 21.0.0.8
21.0.0.9: WebSphere Application Server Liberty 21.0.0.9
21.0.0.1: WebSphere Application Server Liberty 21.0.0.1
21.0.0.2: WebSphere Application Server Liberty 21.0.0.2
21.0.0.10: WebSphere Application Server Liberty 21.0.0.10
21.0.0.11: WebSphere Application Server Liberty 21.0.0.11
21.0.0.12: WebSphere Application Server Liberty 21.0.0.12
22.0.0.1: WebSphere Application Server Liberty 22.0.0.1
22.0.0.2: WebSphere Application Server Liberty 22.0.0.2
22.0.0.3: WebSphere Application Server Liberty 22.0.0.3
22.0.0.4: WebSphere Application Server Liberty 22.0.0.4
APAR status
Closed as program error.
Error description
At 17.0.0.2 and beyond, work done for the split to commercial and open source versions of liberty accidentally enabled native direct ByteBuffer support. This support is enabled regardless of whether the z/OS asyncio support in liberty is in use or not. On common paths for http response flush or inbound request handling the memory obtained this way is not freed. This leads to a leak in 64 bit private. In the customer case this was for both LE HEAPPOOL64 cellpool 11 and 5, although this might vary depending on the request payload / bodies. This APAR will disable this support while additional testing is done. It will also resolve a small cellpool 5 leak associated with AsyncIO CompletionKey and ResultHandler classes.
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: All users of IBM WebSphere Application * * Server Liberty for z/OS * **************************************************************** * PROBLEM DESCRIPTION: Liberty on z/OS memory leak in 64-bit * * private due to custom DirectByteBuffer * * allocation support * **************************************************************** * RECOMMENDATION: * **************************************************************** The WebSphere Liberty for z/OS Async I/O feature includes a custom library for allocating DirectByteBuffers. This custom support does not include automatic memory management and requires the caller to explicitly delete the buffer when it is no longer in use. This support was inadvertently enabled for use beyond the Async I/O feature, causing a leak of the byte buffers in areas of code that rely on automatic memory management. The WebSphere Liberty code has defined pool sizes that it uses for allocation of DirectByteBuffers, therefore the size of the leaked areas relate directly to these pool sizes and can vary. For example, in some cases the leaked storage will contain HTTP requests and responses and the size of those requests and responses will dictate which pool size is used for the native allocation request. An LE Heappool Trace (HPT) of this issue will show a pattern of allocations from native routine "com/ibm/ws/zos/asyncio/ZOSAsyncIOSupport::allocateDirectByteBuf fer(J)Ljava/nio/ByteBuffer;" in libzNativeServices.so on executor threads named Default Executor-thread-<int>, with no corresponding releaseDirectByteBuffer() calls. Also, fixed within this APAR is a small leak in the CompletionKey class. This class uses DirectByteBuffers for managing its I/O requests. The size of these allocation requests fit into the smallest buffer pool of 1024 in size.
Problem conclusion
Code has been modified to disable the custom native routines for allocateDirectByteBuffer and releaseDirectByteBuffer. The WebSphere Liberty code now uses the JDK java.nio.ByteBuffer.allocateDirect method for obtaining DirectByteBuffers Code has also been modified in the Async I/O channel to properly re-use and free the related DirectByteBuffer allocations. This issue is fixed by Open Liberty GitHub issue 3160. For more information, see https://github.com/OpenLiberty/open- liberty/issues/3160. The fix for this APAR is currently targeted for inclusion in fix pack 18.0.0.2. Please refer to the Recommended Updates page for delivery information: http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980
Temporary fix
Comments
APAR Information
APAR number
PI96954
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
2018-04-19
Closed date
2018-05-02
Last modified date
2018-05-02
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
Document Information
Modified date:
04 May 2022