In Bitbucket Server 4.11 adaptive throttling increased the maximum number of concurrent hosting operations concurrently runnable from:

1.5*${scaling.concurrency}

to

12*${scaling.concurrency}

This maximum appears to be too high and has caused problems such as:

• Out of memory errors
• Massive NFS performance degradation
• Insufficient protection from adaptive throttling problems such as BSERVDEV-15333

Workaround:
In Bitbucket Server 5.6.0 and later the value will be set like so:

throttle.resource.scm-hosting.adaptive.limit.max=4*${scaling.concurrency}

For Bitbucket Server 4.11 to 5.5 the same effect can be achieved by adding the above line to the bitbucket.properties file and then rebooting the instance. It is recommend that any cluster installation consider setting this limit to avoid saturating the NFS server with a large number of concurrent requests.