Hi, We are pleased to announce the 2.9.7 (EOL) and 2.10.6 stable releases of the LTTng-UST 2.9 and 2.10 stable branches. LTTng-UST, the Linux Trace Toolkit Next Generation Userspace Tracer, is a low-overhead application tracer. The library "liblttng-ust" enables tracing of applications and libraries. * New in this release: Important fixes to the lttng-ust fd tracker (liblttng-ust-fd.so) were done, taking care of locking the fd tracker across fork() in the liblttng-ust-fork.so wrapper, eliminating hangs observed in the child if the parent was executing close() concurrently with fork(). Also, given that close() is an async-signal-safe function, ensure that the synchronization strategy is robust against signals by disabling signals and using a TLS nesting counter when taking the fd tracker lock. [1, 2] Another important fix to the lttng-ust fd tracker is disabling thread cancellation around fd tracker lock, and locking the fd tracker across fork() in the liblttng-ust-fork.so wrapper. Failure to do so causes deadlocks in child applications if a pthread cancellation is performed on a thread while it ran the liblttng-ust-fd close(3) wrapper. [3] The locking strategy of the LTTng perf counter contexts was revisited to eliminate a deadlock occurring once in a while when using the perf counters context with lttng-ust. [4] Now that the release of LTTng-UST 2.11.0 is imminent, version 2.9.7 marks the end of life (EOL) of the 2.9 stable branch of LTTng-UST. Thanks! Mathieu Project website: http://lttng.org Documentation: http://lttng.org/docs Download link: http://lttng.org/download [1] https://bugs.lttng.org/issues/1199 [2] https://bugs.lttng.org/issues/1200 [3] https://bugs.lttng.org/issues/1201 [4] https://bugs.lttng.org/issues/1202 -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
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