Otterdog's AnyIO process-pool workers have a vulnerability where stderr is connected to a pipe but never drained, causing the pipe to fill and block indefinitely if too much data is written to stderr. This can cause the process-pool call to hang. The issue affects versions from 1.0.1 up to but not including 1.3.4_1. A fix is available in version 1.3.4_1. Closing sys.stderr in the target function can mitigate the deadlock risk.