DB2 - Problembeschreibung
Problem IC63635 | Status: Geschlossen |
MEMORY LEAK IN APPLICATION SHARED MEMORY IF INTRA_PARALLEL IS ON AND THE INSTANCE IS DPF. | |
Produkt: | |
DB2 FOR LUW / DB2FORLUW / 970 - DB2 | |
Problembeschreibung: | |
When a query is compiled, the executable form of the query is called a section. In a DPF database, the section may get logically divided into subsections, where each subsection gets executed within it's own agent thread. When this query is invoked, there are a set of steps that will distribute the section into those subagents. There are various internal memory areas that are used in order to perform this operation of distributing the section into each subagent. Further, when a query is done executing, the sections will be cached in memory so that they can be re-used quickly. The internal memory areas associated with the section remain allocated to facilitate fast section re-use and is good for performance. However, a logic problem exists that is unique to a situation where the database is both DPF, and INTRA_PARALLEL is on. When a section get's re-used in this scenario, there exists a faulty codepath that may assign some internal memory without first checking if it already exists. This results in overwriting the memory address for the previous allocation without first freeing it. Because of this, over a period of time when hitting this codepath, the memory allocations in this area will continue to increase, and this is the perceived memory leak. | |
Problem-Zusammenfassung: | |
Problem Description: MEMORY LEAK IN APPLICATION SHARED MEMORY IF INTRA_PARALLEL IS ON AND THE INSTANCE IS DPF. Problem Summary: When a query is compiled, the executable form of the query is called a section. In a DPF database, the section may get logically divided into subsections, where each subsection gets executed within it's own agent thread. When this query is invoked, there are a set of steps that will distribute the section into those subagents. There are various internal memory areas that are used in order to perform this operation of distributing the section into each subagent. Further, when a query is done executing, the sections will be cached in memory so that they can be re-used quickly. The internal memory areas associated with the section remain allocated to facilitate fast section re-use and is good for performance. However, a logic problem exists that is unique to a situation where the database is both DPF, and INTRA_PARALLEL is on. When a section get's re-used in this scenario, there exists a faulty codepath that may assign some internal memory without first checking if it already exists. This results in overwriting the memory address for the previous allocation without first freeing it. Because of this, over a period of time when hitting this codepath, the memory allocations in this area will continue to increase, and this is the perceived memory leak. | |
Local-Fix: | |
n/a | |
verfügbare FixPacks: | |
DB2 Version 9.7 Fix Pack 2 for Linux, UNIX, and Windows | |
Lösung | |
Problem is first fixed in Version 9.7 Fix Pack 2 | |
Workaround | |
n/a | |
Bug-Verfolgung | |
Vorgänger : APAR is sysrouted TO one or more of the following: IZ67926 Nachfolger : | |
Weitere Daten | |
Datum - Problem gemeldet : Datum - Problem geschlossen : Datum - der letzten Änderung: | 08.10.2009 13.05.2010 13.05.2010 |
Problem behoben ab folgender Versionen (IBM BugInfos) | |
9.7.FP2 | |
Problem behoben lt. FixList in der Version | |
9.7.0.2 |