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[JENKINS-19400] Configurable retention system for lazy-loaded build references #14887
Description
Since 1.485 Jenkins keeps lazy-loaded builds held via SoftReference. This is normally appropriate—you want to hold them as long as possible, but without exhausting the heap. Still, there are reasons why you would prefer a different strategy. If you are pushing up against heap limits, other lazy-loading bugs might cause Jenkins to repeatedly load and then drop build records, causing slow performance and lots of disk I/O. If you want to reproduce a lazy-loading bug, the unpredictability of soft reference GC complicates things. So there should be an option (I guess a system property) to control how a BuildRef holds its referent:
1. As a soft reference, as now.
2. Using a hard reference, never released. (This is not the same as pre-1.485 behavior since the first load is still lazy.)
3. A hard reference released after a certain amount of time has elapsed since the last time the reference was traversed.
4. A hard reference so long as the maximum number of such references is not exceeded (i.e. a LRU list).
5. Not held at all (just for testing behavior of initial load without actually needing to restart Jenkins).
6. Perhaps soft or weak variants of #3 and #4, i.e. initially a hard reference, then downgraded rather than released entirely.
Originally reported by 
jglick, imported from: Configurable retention system for lazy-loaded build references
- assignee: jglick
- status: Resolved
- priority: Major
- component(s): core
- label(s): lazy-loading, memory, performance, testing
- resolution: Fixed
- resolved: 2014-01-09T02:14:39+00:00
- votes: 2
- watchers: 6
- imported: 2025-11-24
Raw content of original issue
Since 1.485 Jenkins keeps lazy-loaded builds held via SoftReference. This is normally appropriate—you want to hold them as long as possible, but without exhausting the heap. Still, there are reasons why you would prefer a different strategy. If you are pushing up against heap limits, other lazy-loading bugs might cause Jenkins to repeatedly load and then drop build records, causing slow performance and lots of disk I/O. If you want to reproduce a lazy-loading bug, the unpredictability of soft reference GC complicates things. So there should be an option (I guess a system property) to control how a BuildRef holds its referent:
1. As a soft reference, as now. 2. Using a hard reference, never released. (This is not the same as pre-1.485 behavior since the first load is still lazy.) 3. A hard reference released after a certain amount of time has elapsed since the last time the reference was traversed. 4. A hard reference so long as the maximum number of such references is not exceeded (i.e. a LRU list). 5. Not held at all (just for testing behavior of initial load without actually needing to restart Jenkins). 6. Perhaps soft or weak variants of #3 and #4, i.e. initially a hard reference, then downgraded rather than released entirely.
Activity
jenkins-infra-bot commentedon Sep 18, 2013
Raw content of original comment:
I agree this is a good change.
One possibly easy way to fix this is by having another strong reference to the build from BuildRef as opposed to make it not to extend WeakReference.
jenkins-infra-bot commentedon Jan 9, 2014
Raw content of original comment:
Code changed in jenkins
User: Jesse Glick
Path:
core/src/main/java/jenkins/model/lazy/AbstractLazyLoadRunMap.java
core/src/main/java/jenkins/model/lazy/BuildReference.java
http://jenkins-ci.org/commit/jenkins/89d7570ddd143c197d394bf2b4f5b34e15cbecdc
Log:
[FIXED JENKINS-19400] Configurable retention system for lazy-loaded build references.
jenkins-infra-bot commentedon Jan 9, 2014
Raw content of original comment:
Code changed in jenkins
User: Jesse Glick
Path:
changelog.html
core/src/main/java/jenkins/model/lazy/BuildReference.java
http://jenkins-ci.org/commit/jenkins/bbe36a5aaa862d0d93430b73ae668e131c3c9120
Log:
[FIXED JENKINS-19400] Noting merge of #1055: BuildReference.HolderFactory.
Compare: 0e00797...bbe36a5
jenkins-infra-bot commentedon Jan 9, 2014
Raw content of original comment:
Jesse Glick : bbe36a5aaa862d0d93430b73ae668e131c3c9120 Files :
Integrated in
jenkins_main_trunk #3155
[FIXED JENKINS-19400] Configurable retention system for lazy-loaded build references. (Revision 89d7570)
[FIXED JENKINS-19400] Noting merge of #1055: BuildReference.HolderFactory. (Revision bbe36a5)
Result = SUCCESS
Jesse Glick : 89d7570ddd143c197d394bf2b4f5b34e15cbecdc
Files :
Jesse Glick : bbe36a5aaa862d0d93430b73ae668e131c3c9120
Files :