[2019-08] [threads] clear small_id_key TLS when unregistering a thread #17015
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Fixes ``` * thread mono#12, name = 'tid_a507', stop reason = EXC_BREAKPOINT (code=1, subcode=0x1be66144) * frame #0: 0x1be66144 libsystem_c.dylib`__abort + 184 frame mono#1: 0x1be6608c libsystem_c.dylib`abort + 152 frame mono#2: 0x003e1fa0 monotouchtest`log_callback(log_domain=0x00000000, log_level="error", message="* Assertion at ../../../../../mono/utils/hazard-pointer.c:158, condition `mono_bitset_test_fast (small_id_table, id)' not met\n", fatal=4, user_data=0x00000000) at runtime.m:1251:3 frame mono#3: 0x003abf44 monotouchtest`monoeg_g_logv_nofree(log_domain=0x00000000, log_level=G_LOG_LEVEL_ERROR, format=<unavailable>, args=<unavailable>) at goutput.c:149:2 [opt] frame mono#4: 0x003abfb4 monotouchtest`monoeg_assertion_message(format=<unavailable>) at goutput.c:184:22 [opt] frame mono#5: 0x003904dc monotouchtest`mono_thread_small_id_free(id=<unavailable>) at hazard-pointer.c:0:2 [opt] frame mono#6: 0x003a0a74 monotouchtest`unregister_thread(arg=0x15c88400) at mono-threads.c:588:2 [opt] frame mono#7: 0x00336110 monotouchtest`mono_thread_detach_if_exiting at threads.c:1571:4 [opt] frame mono#8: 0x003e7a14 monotouchtest`::xamarin_release_trampoline(self=0x166452f0, sel="release") at trampolines.m:644:3 frame mono#9: 0x001cdc40 monotouchtest`::-[__Xamarin_NSTimerActionDispatcher release](self=0x166452f0, _cmd="release") at registrar.m:83445:3 frame mono#10: 0x1ce2ae68 Foundation`_timerRelease + 80 frame mono#11: 0x1c31b56c CoreFoundation`CFRunLoopTimerInvalidate + 612 frame mono#12: 0x1c31a554 CoreFoundation`__CFRunLoopTimerDeallocate + 32 frame mono#13: 0x1c31dde4 CoreFoundation`_CFRelease + 220 frame mono#14: 0x1c2be6e8 CoreFoundation`__CFArrayReleaseValues + 500 frame mono#15: 0x1c2be4c4 CoreFoundation`CFArrayRemoveAllValues + 104 frame mono#16: 0x1c31ff64 CoreFoundation`__CFSetApplyFunction_block_invoke + 24 frame mono#17: 0x1c3b2e18 CoreFoundation`CFBasicHashApply + 116 frame mono#18: 0x1c31ff10 CoreFoundation`CFSetApplyFunction + 160 frame mono#19: 0x1c3152cc CoreFoundation`__CFRunLoopDeallocate + 204 frame mono#20: 0x1c31dde4 CoreFoundation`_CFRelease + 220 frame mono#21: 0x1c304a80 CoreFoundation`__CFTSDFinalize + 144 frame mono#22: 0x1bfa324c libsystem_pthread.dylib`_pthread_tsd_cleanup + 644 frame mono#23: 0x1bf9cc08 libsystem_pthread.dylib`_pthread_exit + 80 frame mono#24: 0x1bf9af24 libsystem_pthread.dylib`pthread_exit + 36 frame mono#25: 0x0039df84 monotouchtest`mono_threads_platform_exit(exit_code=<unavailable>) at mono-threads-posix.c:145:2 [opt] frame mono#26: 0x0033bb84 monotouchtest`start_wrapper(data=0x1609e1c0) at threads.c:1296:2 [opt] frame mono#27: 0x1bf9b914 libsystem_pthread.dylib`_pthread_body + 128 frame mono#28: 0x1bf9b874 libsystem_pthread.dylib`_pthread_start + 44 frame mono#29: 0x1bfa3b94 libsystem_pthread.dylib`thread_start + 4 ```
Co-Authored-By: Aleksey Kliger (λgeek) <[email protected]>
lewurm
approved these changes
Sep 24, 2019
Contributor
|
@monojenkins squash |
Contributor
Author
|
Cannot squash because the following required status checks are not successful:
|
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Fixes
Debugged by @lambdageek. Contributes to #10641
Edit: C/p into PR description so it's in the commit message:
We think what happens is:
start_wrapperrunsunregister_threadwhen the thread is exiting. At that point thesmall_idfor the thread is cleared from the hazard pointer bitset bymono_thread_small_id_free (small_id)Some other TLS destructor runs and attaches the thread again (which runs
mono_thread_info_register_small_idwhich first callsmono_thread_info_get_small_idwhich tries to get the small id from thesmall_id_keyTLS key and so the newMonoThreadInfohas the samesmall_idas the previously destroyedMonoThreadInfo- but the hazard pointer bitset is not updated).This other TLS destructor runs and calls
mono_thread_detach_if_exitingwhich callsunregister_threadagain.unregister_threadcallsmono_thread_small_id_free (small_id)a second time which asserts because we already cleared that id from the hazard pointer bitset.Backport of #16973.
/cc @lewurm