Hi,
A bit of a long shot, but since leveldb is used by QtWebEngine this might ring
a bell to someone here:
Below is a bit of backtrace of a Qt application (KDevelop) on Mac in which I've
started experimenting with using leveldb. Under certain conditions the entire
app freezes, and then I see this in the debugger:
* thread #1: tid = 0x1105e90, 0x00007fff8f75eb16
libsystem_kernel.dylib`syscall_thread_switch + 10, queue =
'com.apple.main-thread', stop reason = signal SIGSTOP
* frame #0: 0x00007fff8f75eb16 libsystem_kernel.dylib`syscall_thread_switch +
10
frame #1: 0x00007fff92529df6 libsystem_platform.dylib`_OSSpinLockLockSlow +
63
frame #2: 0x00007fff8d86890d libsystem_pthread.dylib`_pthread_testcancel +
28
frame #3: 0x00007fff99864d2e libsystem_c.dylib`nanosleep + 42
frame #4: 0x000000010b75b7b1
libtcmalloc.4.dylib`base::internal::SpinLockDelay(int volatile*, int, int) + 122
frame #5: 0x000000010b75b6af libtcmalloc.4.dylib`SpinLock::SlowLock() + 41
frame #6: 0x000000010b74fe00
libtcmalloc.4.dylib`tcmalloc::CentralCacheLockAll() + 56
frame #7: 0x00007fff97676cd1 libsystem_malloc.dylib`_malloc_fork_prepare +
49
frame #8: 0x00007fff997fa161 libsystem_c.dylib`fork + 12
frame #9: 0x0000000106be1c63 QtCore`forkfd(flags=<unavailable>,
ppid=0x00007fff5c5e650c) + 483 at forkfd.c:691
frame #10: 0x0000000106bd5801
QtCore`QProcessPrivate::startProcess(this=0x0000000129019100) + 3537 at
qprocess_unix.cpp:471
frame #11: 0x0000000106bd180f
QtCore`QProcessPrivate::start(this=0x0000000129019100, mode=<unavailable>) +
431 at qprocess.cpp:2177
frame #12: 0x0000000106bd14ca QtCore`QProcess::start(this=<unavailable>,
program=<unavailable>, arguments=0x00000001289e5a28, mode=<unavailable>) + 154
at qprocess.cpp:2089
SNIP
Further frames are completely unrelated to the leveldb code I'm writing. It
looks like leveldb makes a process-wide change that causes malloc() to redirect
to libtcmalloc. Not that I mind the idea, but it seems clear that tcmalloc
isn't "expecting to be called" here, and deadlocks.
Has anyone seen this kind of behaviour before?
Thanks,
R.
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