ywkaras commented on issue #10129: URL: https://github.com/apache/trafficserver/issues/10129#issuecomment-1662839243
I think a general description of the problem scenario is: 1. While it has a mutex M locked, a function F makes a call that can trigger the dynamic loading of a shared library S1. 2. F is called during the non-local dynamic initialization of another shared library S2. It appears to be the case that the runtime has an implicit mutex MS, which is locked during while any shared library is dynamically loaded. It seems MS is kept locked during the non-local initialization of the library being loaded. 3. F is also called from the core executable, and there is a race condition between this/these calls for F, and the loading of S2. The deadlock scenario is: 1. Thread T1 locks MS, starts loading S2, and calls F. 2. Thread T2 calls F, and locks M. T2 then blocks on MS, because it needs to load S1. 3. T1, within its call to F, blocks on M. Deadlock. One possible solution is to trigger the loading of S1 during initialization while there is still just one thread. But this will only work if the dynamic loader checks if a library is loaded without locking MS, and only locks it if it loading the library is necessary. There may be tricky ways for avoid calling PCRE functions during non-local dynamic initialization. But, ew. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: issues-unsubscr...@trafficserver.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
