mirror of git://sourceware.org/git/glibc.git
114 lines
4.2 KiB
C
114 lines
4.2 KiB
C
/* Bug 22111: Test that threads do not leak their per thread cache.
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Copyright (C) 2015-2018 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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/* The point of this test is to start and exit a large number of
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threads, while at the same time looking to see if the used
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memory grows with each round of threads run. If the memory
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grows above some linear bound we declare the test failed and
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that the malloc implementation is leaking memory with each
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thread. This is a good indicator that the thread local cache
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is leaking chunks. */
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#include <stdio.h>
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#include <stdlib.h>
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#include <malloc.h>
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#include <pthread.h>
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#include <assert.h>
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#include <support/check.h>
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#include <support/support.h>
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#include <support/xthread.h>
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void *
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worker (void *data)
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{
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void *ret;
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/* Allocate an arbitrary amount of memory that is known to fit into
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the thread local cache (tcache). If we have at least 64 bins
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(default e.g. TCACHE_MAX_BINS) we should be able to allocate 32
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bytes and force malloc to fill the tcache. We are assuming tcahce
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init happens at the first small alloc, but it might in the future
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be deferred to some other point. Therefore to future proof this
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test we include a full alloc/free/alloc cycle for the thread. We
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need a compiler barrier to avoid the removal of the useless
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alloc/free. We send some memory back to main to have the memory
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freed after the thread dies, as just another check that the chunks
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that were previously in the tcache are still OK to free after
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thread death. */
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ret = xmalloc (32);
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__asm__ volatile ("" ::: "memory");
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free (ret);
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return (void *) xmalloc (32);
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}
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static int
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do_test (void)
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{
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pthread_t *thread;
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struct mallinfo info_before, info_after;
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void *retval;
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/* This is an arbitrary choice. We choose a total of THREADS
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threads created and joined. This gives us enough iterations to
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show a leak. */
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int threads = 100000;
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/* Avoid there being 0 malloc'd data at this point by allocating the
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pthread_t required to run the test. */
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thread = (pthread_t *) xcalloc (1, sizeof (pthread_t));
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info_before = mallinfo ();
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assert (info_before.uordblks != 0);
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printf ("INFO: %d (bytes) are in use before starting threads.\n",
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info_before.uordblks);
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for (int loop = 0; loop < threads; loop++)
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{
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*thread = xpthread_create (NULL, worker, NULL);
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retval = xpthread_join (*thread);
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free (retval);
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}
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info_after = mallinfo ();
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printf ("INFO: %d (bytes) are in use after all threads joined.\n",
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info_after.uordblks);
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/* We need to compare the memory in use before and the memory in use
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after starting and joining THREADS threads. We almost always grow
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memory slightly, but not much. Consider that if even 1-byte leaked
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per thread we'd have THREADS bytes of additional memory, and in
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general the in-use at the start of main is quite low. We will
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always leak a full malloc chunk, and never just 1-byte, therefore
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anything above "+ threads" from the start (constant offset) is a
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leak. Obviously this assumes no thread-related malloc'd internal
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libc data structures persist beyond the thread death, and any that
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did would limit the number of times you could call pthread_create,
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which is a QoI we'd want to detect and fix. */
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if (info_after.uordblks > (info_before.uordblks + threads))
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FAIL_EXIT1 ("Memory usage after threads is too high.\n");
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/* Did not detect excessive memory usage. */
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free (thread);
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exit (0);
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}
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#define TIMEOUT 50
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#include <support/test-driver.c>
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