Windows 10, CentOS 6.6
Our application generates lot of concurrent read requests to subversion using svn: protocol. When we tested the multithreaded mode of svnserve after upgrade to 1.9.3, we noticed strange 'deadlock-like' behaviour: at some point all the requests are blocked in svnserve and wait there for a few minutes (3 to 5 minutes, no CPU activity), after which they continue to work. This is making our application significantly slower. We observed this behaviour on both Windows 10 and CentOS 6.6.
The workaround is to run svnserve without -T switch, i.e. not using multithreaded mode.
Here is a sample of thread dump of svnserve.exe during the 'deadlock' obtained on Windows 10 using Process Explorer:
The similar stack can be seen with other threads too.