If the app server can't allocate memory to fork a process, then something is very wrong with the app server. Once we've identified and fixed the memory leak, if we still see the that OOPS then it might be worth considering this.
Bringing things like this in process has the risk of introducing memory leaks or crashes into the app server (see the problems with the lxml dependency of hwdb, for instance), so it isn't always obvious that in process is better.
If the app server can't allocate memory to fork a process, then something is very wrong with the app server. Once we've identified and fixed the memory leak, if we still see the that OOPS then it might be worth considering this.
Bringing things like this in process has the risk of introducing memory leaks or crashes into the app server (see the problems with the lxml dependency of hwdb, for instance), so it isn't always obvious that in process is better.