> did you have a method/tool to debug (from book, or chatting with others) Specifically for this issue, I ended up forking valgrind to add multi-threaded watc

> did you have a method/tool to debug (from book, or chatting with others) Specifically for this issue, I ended up forking valgrind to add multi-threaded watchpoints in code (this was debugging shared memory refcounts, so I had to extend it to log negative refcounts only). The origin of those patches are here - https://valgrind.org/downloads/variants.html?rjw https://valgrind.org/downloads/variants.html?rjw