On Mon, 29 Nov 2004 16:41:49 -0500, Beman Dawes <bdawes@acm.org> wrote:
Caleb, could you please do one more thing on this: read the docs and see if your answer is obvious from the docs. If not, could you please submit a path clarifying the docs the need to join.
FYI I've managed to produce this OOM condition with Solaris pthreads, so its not a Linux or Boost issue. Attached is a simple program that probes this limit using only pthreads calls. On Solaris I hit the memory limit after 2,714 threads and on Linux 2.4.21-9.ELsmp I hit it at 1,020. I don't think the memory leak issue is discussed anywhere in the Boost.Threads documentation, or if it is I'm unable to find it. Because threads are automatically detached in the thread dtor, the only way for this leak to take place is by creating threads on the heap and not deleting/joining them, which is what the OP was doing. There is the following text in http://boost.org/doc/html/thread.html, under Description: "A thread of execution is said to be "finished" or to have "finished execution" when its initial function returns or is terminated. This includes completion of all thread cleanup handlers, and completion of the normal C++ function return behaviors, such as destruction of automatic storage (stack) objects and releasing any associated implementation resources." Perhaps the following paragraph could be added in another callout at the bottom of this section or below the "thread construct/copy/destruct" section: "With some platform-specific thread libraries (notably POSIX threads), the stack space of a joinable thread is not automatically cleaned up until it has been joined. When thread objects are allocated on the heap (e.g. via operator new or thread_group::create), it is the responsibility of the user of Boost.Threads to ensure these threads have been either detached or joined in order to avoid memory leaks." Also, here are some formatting oddities I noticed in the documentation from my reading just now: On page http://boost.org/doc/html/threads/rationale.html, in the Comparison section: * 2. Comparison: creation of a thread that's later joined create_thread(&bar);thrd->join(); should be create_thread(&bar); thrd->join(); * 4. Comparison: creation of several threads in a loop which are later joined. for (int i= 0; i<NUM_THREADS; ++i)threads[i]->join(); should be for (int i= 0; i<NUM_THREADS; ++i) threads[i]->join(); -- Caleb Epstein caleb dot epstein at gmail dot com