The wt4333_handle_locks test is failing about 50% of the time in the Jenkins wiredtiger-valgrind job. It is failing with an error about exceeding the maximum threads allowed by valgrind. Here's an example from http://build.wiredtiger.com:8080/job/wiredtiger-valgrind/3066/console:

FAIL: test_wt4333_handle_locks
==============================

Use --max-threads=INT to specify a larger number of threads
and rerun valgrind

valgrind: the 'impossible' happened:
   Max number of threads is too low

Thread 1: status = VgTs_Runnable (lwpid 32578)
Thread 2: status = VgTs_WaitSys (lwpid 19702)
...
Thread 499: status = VgTs_WaitSys (lwpid 19072)

All failures show up to thread 499. This implies the valgrind thread limit is 500.

What is interesting is that wt4333_handle_locks always runs through a configuration that starts 600 worker threads and about half the time the test passes in valgrind. So I have no idea why sometimes 600 threads can succeed.