JDK-8183925 : Decouple crash protection from watcher thread
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: runtime
  • Affected Version: 10
  • Priority: P4
  • Status: Resolved
  • Resolution: Fixed
  • Submitted: 2017-07-06
  • Updated: 2024-09-11
  • Resolved: 2017-07-07
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JDK 10 Other
10 b21Fixed openjdk8u262Fixed
Related Reports
Relates :  
JDK-8257192 - Integrate AArch64 JIT port into 8u
Relates :  
JDK-8184339 - Thread::current_or_null() shall not assert if Posix TLS is not yet initialized
Description
Upcomming changes in tracing backend no longer rely on watcher thread.
Crash protection needs to be decoupled from watcher thread.
Comments
Sorry Robbin, I must have misread something.
19-08-2017
URL: http://hg.openjdk.java.net/jdk10/jdk10/hotspot/rev/786437c6344b User: jwilhelm Date: 2017-08-18 18:01:35 +0000
18-08-2017
David, static bool is_crash_protected(Thread* thr) { return _crash_protection != NULL && _protected_thread == thr; } The _protected_thread can never be NULL if _crash_protection is none NULL. Which this assert protected against: assert(_protected_thread != NULL, "Cannot crash protect a NULL thread"); So if we are in early startup and current thread is NULL, it can never be crash protected. Thus we either have a different thread crash protected e.g. _crash_protection != NULL is true, but _protected_thread == thr will be false, so is_crash_protected will return false. Or _crash_protection != NULL is false and we will return false.
18-08-2017
Robbin, This assertion looks wrong to me: + assert(!os::ThreadCrashProtection::is_crash_protected(Thread::current_or_null()), + "malloc() not allowed when crash protection is set"); If the current thread is NULL, due to call through early os::malloc, and crash protection is not set, is_crash_protected will incorrectly report true because NULL==NULL. The assertion will then fire when it should not.
31-07-2017
URL: http://hg.openjdk.java.net/jdk10/hs/hotspot/rev/786437c6344b User: rehn Date: 2017-07-07 23:01:49 +0000
07-07-2017