What are the circumstances for this to happen?

Code changed in jenkins
User: christ66
Path:
core/src/main/java/hudson/Launcher.java
core/src/main/java/hudson/model/Slave.java
http://jenkins-ci.org/commit/jenkins/d2a2ec589f4728fa2cfa35371155bce7cc95a0a7
Log:
[FIXED JENKINS-21999] If a slave node does not exist it will throw a
null pointer exception. Instead we create a dummy launcher and return
that if it is unable to get the slave node.

Code changed in jenkins
User: Jesse Glick
Path:
core/src/main/java/hudson/Launcher.java
core/src/main/java/hudson/model/Slave.java
http://jenkins-ci.org/commit/jenkins/e7c7bbd541d091923fceb6a2613881944ae8c810
Log:
Merge branch 'JENKINS-21999' of github.com:christ66/jenkins

Code changed in jenkins
User: Jesse Glick
Path:
changelog.html
http://jenkins-ci.org/commit/jenkins/43f218cd79223d96691a0957c7befed6f85ff868
Log:
JENKINS-21999 Noting merge of #1145.

Compare: https://github.com/jenkinsci/jenkins/compare/44a8ec110459...43f218cd7922

Integrated in jenkins_main_trunk #3278
[FIXED JENKINS-21999] If a slave node does not exist it will throw a (Revision d2a2ec589f4728fa2cfa35371155bce7cc95a0a7)
JENKINS-21999 Noting merge of #1145. (Revision 43f218cd79223d96691a0957c7befed6f85ff868)

Result = SUCCESS
schristou88 : d2a2ec589f4728fa2cfa35371155bce7cc95a0a7
Files :

• core/src/main/java/hudson/model/Slave.java
• core/src/main/java/hudson/Launcher.java

Jesse Glick : 43f218cd79223d96691a0957c7befed6f85ff868
Files :

• changelog.html

Any idea when this will make it into an official release? I was actually making a comment yesterday evening when I saw these updates. We're having a similar problem:

Basically, when we start a job on any given node, there's a high chance that the next job queued to run on the same node will attempt to start and then fail with this exception:

FATAL: null
java.lang.NullPointerException
at hudson.model.Slave.createLauncher(Slave.java:348)
at hudson.model.AbstractBuild$AbstractBuildExecution.createLauncher(AbstractBuild.java:564)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:481)
at hudson.model.Run.execute(Run.java:1688)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:231)

I say "high chance" because this exception is fairly reproducible in our systems with some variation. Most often, this occurs in builds triggered used in the Parameterized Build Plugin.

Does anyone have an idea if our issues might be solved by this fix as well?

Clinton Barr: Unless delayed, the change will be in 1.559 to be released in 1.5 weeks or so.

Also observed from Support Core:

WARNING: Could not get content from 'File descriptors (Unix only)' for support bundle 
java.lang.NullPointerException 
	at hudson.model.Slave.createLauncher(Slave.java:347) 
	at com.cloudbees.jenkins.support.impl.FileDescriptorLimit.addContents(FileDescriptorLimit.java:65) 
	at com.cloudbees.jenkins.support.impl.FileDescriptorLimit.addContents(FileDescriptorLimit.java:56) 
	at com.cloudbees.jenkins.support.SupportPlugin.writeBundle(SupportPlugin.java:264) 
	at com.cloudbees.jenkins.support.SupportPlugin.writeBundle(SupportPlugin.java:227) 
	at com.cloudbees.jenkins.support.SupportPlugin$PeriodicWorkImpl$1.run(SupportPlugin.java:543) 
	at java.lang.Thread.run(Thread.java:780)

Code changed in jenkins
User: Jesse Glick
Path:
src/main/java/com/cloudbees/jenkins/support/impl/FileDescriptorLimit.java
http://jenkins-ci.org/commit/support-core-plugin/44539f3a597ed5c37436be28d1087de0aacdd3be
Log:
JENKINS-21999 Workaround: ignore an offline slave.

Code changed in jenkins
User: christ66
Path:
core/src/main/java/hudson/Launcher.java
core/src/main/java/hudson/model/Slave.java
http://jenkins-ci.org/commit/jenkins/7946d9fa3e00295298294137a3b263d2c6def9ff
Log:
[FIXED JENKINS-21999] If a slave node does not exist it will throw a
null pointer exception. Instead we create a dummy launcher and return
that if it is unable to get the slave node.

(cherry picked from commit d2a2ec589f4728fa2cfa35371155bce7cc95a0a7)