The thread sanitizer on Linux is reporting that I have race conditions in
libswiftcore. I eliminated enough code down to this trivial example. Is
there really a race condition here or are these bogus errors?
let count = 1000
var items = [[UInt8]?](repeating: nil, count: count)
DispatchQueue.concurrentPerform(iterations: count) {
items[$0] = [UInt8](repeating: 7, count: 10)
}
My real scenario is retrieving data asynchronously, so I just threw in a
buffer assignment.
Thanks, Ed
==================
WARNING: ThreadSanitizer: data race (pid=30720)
Read of size 8 at 0x7d9000008028 by thread T16:
#0 memcpy <null> (libtsan.so.0+0x00000002617a)
#1 _TwCcOs31_ClosedRangeIndexRepresentation <null>
(libswiftCore.so+0x00000027e0fa)
Previous write of size 8 at 0x7d9000008028 by main thread:
#0 memcpy <null> (libtsan.so.0+0x00000002617a)
#1 _TwCcOs31_ClosedRangeIndexRepresentation <null>
(libswiftCore.so+0x00000027e0fa)
Location is heap block of size 8032 at 0x7d9000008000 allocated by main
thread:
#0 malloc <null> (libtsan.so.0+0x0000000254a3)
#1 swift_slowAlloc <null> (libswiftCore.so+0x0000002ee3e5)
Thread T16 (tid=30917, running) created by main thread at:
#0 pthread_create <null> (libtsan.so.0+0x000000027577)
#1 manager_workqueue_additem
/home/buildnode/disk2/workspace/oss-swift-3.0-package-linux-ubuntu-16_04/swift-corelibs-libdispatch/libpwq/src/posix/manager.c:815
(libdispatch.so+0x00000007c6b1)
SUMMARY: ThreadSanitizer: data race ??:0 memcpy
==================
==================
WARNING: ThreadSanitizer: data race (pid=30720)
Write of size 8 at 0x7d0c00015d80 by thread T16:
#0 free <null> (libtsan.so.0+0x000000025819)
#1 _TwXxOs31_ClosedRangeIndexRepresentation <null>
(libswiftCore.so+0x00000027e071)
Previous write of size 8 at 0x7d0c00015d80 by main thread:
#0 malloc <null> (libtsan.so.0+0x0000000254a3)
#1 swift_slowAlloc <null> (libswiftCore.so+0x0000002ee3e5)
Thread T16 (tid=30917, running) created by main thread at:
#0 pthread_create <null> (libtsan.so.0+0x000000027577)
#1 manager_workqueue_additem
/home/buildnode/disk2/workspace/oss-swift-3.0-package-linux-ubuntu-16_04/swift-corelibs-libdispatch/libpwq/src/posix/manager.c:815
(libdispatch.so+0x00000007c6b1)
SUMMARY: ThreadSanitizer: data race ??:0 __interceptor_free
==================
==================
WARNING: ThreadSanitizer: data race (pid=30720)
Write of size 8 at 0x7d900000a028 by thread T20:
#0 free <null> (libtsan.so.0+0x000000025819)
#1 _TZFSa11_copyBufferfRGVs22_ContiguousArrayBufferx_T_ <null>
(libswiftCore.so+0x00000010884e)
Previous read of size 8 at 0x7d900000a028 by thread T17:
#0 memcpy <null> (libtsan.so.0+0x00000002617a)
#1 _TwCcOs31_ClosedRangeIndexRepresentation <null>
(libswiftCore.so+0x00000027e0fa)
Thread T20 (tid=30921, running) created by main thread at:
#0 pthread_create <null> (libtsan.so.0+0x000000027577)
#1 manager_workqueue_additem
/home/buildnode/disk2/workspace/oss-swift-3.0-package-linux-ubuntu-16_04/swift-corelibs-libdispatch/libpwq/src/posix/manager.c:815
(libdispatch.so+0x00000007c6b1)
Thread T17 (tid=30918, running) created by main thread at:
#0 pthread_create <null> (libtsan.so.0+0x000000027577)
#1 manager_workqueue_additem
/home/buildnode/disk2/workspace/oss-swift-3.0-package-linux-ubuntu-16_04/swift-corelibs-libdispatch/libpwq/src/posix/manager.c:815
(libdispatch.so+0x00000007c6b1)
SUMMARY: ThreadSanitizer: data race ??:0 __interceptor_free
==================
==================
WARNING: ThreadSanitizer: data race (pid=30720)
Read of size 8 at 0x7d9000006028 by thread T23:
#0 memcpy <null> (libtsan.so.0+0x00000002617a)
#1 _TwCcOs31_ClosedRangeIndexRepresentation <null>
(libswiftCore.so+0x00000027e0fa)
Previous write of size 8 at 0x7d9000006028 by main thread:
#0 malloc <null> (libtsan.so.0+0x0000000254a3)
#1 swift_slowAlloc <null> (libswiftCore.so+0x0000002ee3e5)
Location is heap block of size 8032 at 0x7d9000006000 allocated by main
thread:
#0 malloc <null> (libtsan.so.0+0x0000000254a3)
#1 swift_slowAlloc <null> (libswiftCore.so+0x0000002ee3e5)
Thread T23 (tid=30924, running) created by main thread at:
#0 pthread_create <null> (libtsan.so.0+0x000000027577)
#1 manager_workqueue_additem
/home/buildnode/disk2/workspace/oss-swift-3.0-package-linux-ubuntu-16_04/swift-corelibs-libdispatch/libpwq/src/posix/manager.c:815
(libdispatch.so+0x00000007c6b1)
SUMMARY: ThreadSanitizer: data race ??:0 memcpy
==================
==================
WARNING: ThreadSanitizer: data race (pid=30720)
Write of size 8 at 0x7d900002e000 by thread T19:
#0 free <null> (libtsan.so.0+0x000000025819)
#1 _TZFSa11_copyBufferfRGVs22_ContiguousArrayBufferx_T_ <null>
(libswiftCore.so+0x000000108859)
Previous write of size 8 at 0x7d900002e000 by thread T20:
#0 malloc <null> (libtsan.so.0+0x0000000254a3)
#1 swift_slowAlloc <null> (libswiftCore.so+0x0000002ee3e5)
Thread T19 (tid=30920, running) created by main thread at:
#0 pthread_create <null> (libtsan.so.0+0x000000027577)
#1 manager_workqueue_additem
/home/buildnode/disk2/workspace/oss-swift-3.0-package-linux-ubuntu-16_04/swift-corelibs-libdispatch/libpwq/src/posix/manager.c:815
(libdispatch.so+0x00000007c6b1)
Thread T20 (tid=30921, running) created by main thread at:
#0 pthread_create <null> (libtsan.so.0+0x000000027577)
#1 manager_workqueue_additem
/home/buildnode/disk2/workspace/oss-swift-3.0-package-linux-ubuntu-16_04/swift-corelibs-libdispatch/libpwq/src/posix/manager.c:815
(libdispatch.so+0x00000007c6b1)
SUMMARY: ThreadSanitizer: data race ??:0 __interceptor_free
==================
==================
WARNING: ThreadSanitizer: data race (pid=30720)
Write of size 8 at 0x7d9000004000 by thread T17:
#0 free <null> (libtsan.so.0+0x000000025819)
#1 _TZFSa11_copyBufferfRGVs22_ContiguousArrayBufferx_T_ <null>
(libswiftCore.so+0x00000010884e)
Previous write of size 8 at 0x7d9000004000 by main thread:
#0 malloc <null> (libtsan.so.0+0x0000000254a3)
#1 swift_slowAlloc <null> (libswiftCore.so+0x0000002ee3e5)
Thread T17 (tid=30918, running) created by main thread at:
#0 pthread_create <null> (libtsan.so.0+0x000000027577)
#1 manager_workqueue_additem
/home/buildnode/disk2/workspace/oss-swift-3.0-package-linux-ubuntu-16_04/swift-corelibs-libdispatch/libpwq/src/posix/manager.c:815
(libdispatch.so+0x00000007c6b1)
SUMMARY: ThreadSanitizer: data race ??:0 __interceptor_free
==================
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