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Posted to commits@harmony.apache.org by "Ilya Leviev (JIRA)" <ji...@apache.org> on 2007/05/17 17:06:16 UTC
[jira] Updated: (HARMONY-3902) [drlvm][thread] Race condition at
"thread_native_thin_monitor.c":78 and "thread_java_monitors.c":122
[ https://issues.apache.org/jira/browse/HARMONY-3902?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Ilya Leviev updated HARMONY-3902:
---------------------------------
Attachment: SourceViewScreenshot-1.jpg
Source View screenshot added
> [drlvm][thread] Race condition at "thread_native_thin_monitor.c":78 and "thread_java_monitors.c":122
> ----------------------------------------------------------------------------------------------------
>
> Key: HARMONY-3902
> URL: https://issues.apache.org/jira/browse/HARMONY-3902
> Project: Harmony
> Issue Type: Bug
> Components: DRLVM
> Reporter: Ilya Leviev
> Attachments: SourceViewScreenshot-1.jpg
>
>
> TC report on thread unsafe access that result in race condition that occur during concurrent execution of set_fat_lock_id and jthread_monitor_enter functions.
> Write -> Read data-race
> Memory read at "thread_java_monitors.c":122 conflicts with a prior memory write at "thread_native_thin_monitor.c":78
> Stack Trace:
> Context
> Function void vm_execute_java_method_array(struct _jmethodID *,union jvalue *,union jvalue *) "ini.cpp":60
> Function ExecuteMethod "em_intf.cpp":43
> Function void DrlEMImpl::executeMethod(struct _jmethodID *,union jvalue *,union jvalue *) "drlemimpl.cpp":509
> Function void JIT_execute_method_default(void *,struct _jmethodID *,union jvalue *,union jvalue *) "ini_ia32.cpp":199
> Function vm_invoke_native_array_stub "ini_ia32.cpp":76
> Function class VM_thread * get_thread_ptr_stub(void) "thread_manager.cpp":138
> Function m2n_free_local_handles "m2n_ia32.cpp":268
> Function hythread_thin_monitor_try_enter "thread_native_thin_monitor.c":341
> Function class VM_thread * get_thread_ptr_stub(void) "thread_manager.cpp":138
> Function jthread_monitor_enter "thread_java_monitors.c":68
> 1st Access
> Function m2n_free_local_handles "m2n_ia32.cpp":268
> Function hythread_self "hythread.h":465
> Function class VM_thread * get_thread_ptr_stub(void) "thread_manager.cpp":138
> Function m2n_free_local_handles "m2n_ia32.cpp":268
> Function class VM_thread * get_thread_ptr_stub(void) "thread_manager.cpp":138
> Function hythread_suspend_enable "hythread_ext.h":370
> Function Java_java_lang_VMThreadManager_wait "java_lang_vmthreadmanager.cpp":202
> Function jthread_monitor_timed_wait "thread_java_monitors.c":308
> Function inflate_lock "thread_native_thin_monitor.c":600
> Function set_fat_lock_id "thread_native_thin_monitor.c":78
> "76" "" " lockword&=0x7FF;"
> "77" "" " lockword|=(monitor_id << 11) | 0x80000000;"
> "78" "*" " *lockword_ptr=lockword;"
> "79" "" " apr_memory_rw_barrier();"
> "80" "" " }"
> 2nd Access
> Function void vm_execute_java_method_array(struct _jmethodID *,union jvalue *,union jvalue *) "ini.cpp":60
> Function ExecuteMethod "em_intf.cpp":43
> Function void DrlEMImpl::executeMethod(struct _jmethodID *,union jvalue *,union jvalue *) "drlemimpl.cpp":509
> Function void JIT_execute_method_default(void *,struct _jmethodID *,union jvalue *,union jvalue *) "ini_ia32.cpp":199
> Function vm_invoke_native_array_stub "ini_ia32.cpp":76
> Function class VM_thread * get_thread_ptr_stub(void) "thread_manager.cpp":138
> Function m2n_free_local_handles "m2n_ia32.cpp":268
> Function hythread_thin_monitor_try_enter "thread_native_thin_monitor.c":341
> Function class VM_thread * get_thread_ptr_stub(void) "thread_manager.cpp":138
> Function jthread_monitor_enter "thread_java_monitors.c":122
> "120" "" " lockword = vm_object_get_lockword_addr(monitor);"
> "121" "" " "
> "122" "*" " if (is_fat_lock(*lockword)) {"
> "123" "" " status = hythread_thin_monitor_enter(lockword);"
> "124" "" " if (status != TM_ERROR_NONE) {"
> See also Source View screenshot.
> Notes on Write->Read race condition.
> ------------------------------------
> Write->Read data races occur when one thread writes a shared memory location (address) while another thread concurrently reads the same memory location.
> The shared memory location may be referred to by (variable) name, pointer, or even a function such as memcpy().
> The following example uses a variable name:
> 1st access by first thread
> S1: sharedX = privateA
> 2nd access by second thread
> S2: privateB = sharedX
> If sharedX is a variable visible to all threads and privateA and privateB are local variables visible only to the thread where each was declared,
> concurrent execution of the above statements by multiple threads results in a "race" on the value to be read from sharedX.
> Since the order of execution among threads is unpredictable, it is unknown which value will be available in sharedX to be stored into privateB.
> This results in non-deterministic software, or software prone to produce different results each time it is executed.
> _______________________________________________________________________________________________________________________
> If it not affect correctness of execution I will mark it by special API for prevention of further alarms on this race.
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