kudu: forked process died unexpectedly

this issue is closely related to - https://github.com/projectkudu/kudu/issues/2703 - however, there are no modules involved, this is just a plan node site. That has been working for a number of months.

When running our deploy.sh it would fail quickly after with forked process 5080 died unexpectedly, retry 0, exit code 0xC0000142, errno 11

After some digging, I get the same error when running bash or sh directly from a cmd prompt in either cmd or ps

D:\Program Files (x86)\Git\usr\bin>sh
ls
      3 [main] sh 9008 fork: child -1 - forked process 12524 died unexpectedly, retry 0, exit code 
0xC0000142, errno 11
sh: fork: retry: Resource temporarily unavailable

digging around it appears that this is ultimately coming from the underlying Cygwin installation, and may be related to a high user process count. (unfortunately, I couldn’t find a way to count the user processes without having the forking error)

We did try to scale the app service, and this did allow us to deploy successfully, but once it was scaled down again the error returned. The app is running on a B1, by upgrading to a b2 then that error goes. (downgrading again brings it back)

Upgrading to an S1 also produces the issue.