SSH Fail Intermittently due to upload-pack: Resource temporarily unavailable

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Platform notice: Server and Data Center only. This article only applies to Atlassian products on the Server and Data Center platforms.

Support for Server* products ended on February 15th 2024. If you are running a Server product, you can visit the Atlassian Server end of support announcement to review your migration options.

*Except Fisheye and Crucible


  • SSH git clone fail intermittently while HTTP(S) works as per normal.
  • This is noticed after an upgrade to Bitbucket Server 3.6.0 - 3.10.x

The following appears in the catalina.log

30-Jun-2015 04:38:43.453 SEVERE [ajp-nio-]$SocketProcessor.doRun 
 java.lang.OutOfMemoryError: unable to create new native thread
	at java.lang.Thread.start0(Native Method)
	at java.lang.Thread.start(

The following appears in the atlassian-bitbucket.log

2015-06-29 05:17:36,139 ERROR [ajp-nio-] xxxx @xxxx "GET /scm/something/something.git/info/refs HTTP/1.1" c.a.s.i.s.g.p.h.GitSmartExitHandler something/something_shared[292]: Read request from failed: com.atlassian.utils.process.ProcessException: Non-zero exit code: 255
The following was written to stderr:
error: cannot fork() for git-http-backend: Resource temporarily unavailable 



  • Large Enterprise server with similar environment as follows:


Diagnostic Steps

  • Enable git debug with below will show the debug logging stuck while trying to identity file .ssh cert

    export GIT_TRACE_PACKET=1
    export GIT_TRACE=1
    git clone ssh://admin@<>/something/something.git


The default max thread on Bitbucket Server 3.10.x is too high for an Enterprise server with lots of hyper-threaded cores. This changes was made for BSERV-6868 - Getting issue details... STATUS to fix insufficient threads. However, this is then to be an issue when internal thread pool can grow up to 100 + 20 * 64 = 1380 threads which at some point the server could not create any more threads because it ran out of (virtual) memory.

The following are the default set per Bitbucket Server version:

3.11.0: executor.max.threads=${scaling.concurrency}
3.6.0 - 3.10.x: executor.max.threads=100+20*${scaling.concurrency} (where the later is # of cpu)
2.11.x: executor.max.threads=100



This is a known bug and a workaround would be to re-configure the default value of the executor.max.threads.

  • Shutdown Bitbucket Server
  • Add the following in

  • Startup Bitbucket Server


This bug has been fixed in Bitbucket Server 3.11.0, see BSERV-7616 - Getting issue details... STATUS

Last modified on Mar 30, 2016

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