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Report From: Delphi-BCB/RTL/Delphi/Thread support    [ Add a report in this area ]  
Report #:  103897   Status: Closed
AV in TMonitor.RemoveWaiter
Project:  Delphi Build #:  15.0.3953.35171
Version:    15.1 Submitted By:   Balazs Farkas
Report Type:  Crash / Data loss / Total failure Date Reported:  3/3/2012 8:53:12 AM
Severity:    Critical / Show Stopper Last Updated: 3/14/2012 5:14:02 AM
Platform:    All platforms Internal Tracking #:  
Resolution: Fixed (Resolution Comments) Resolved in Build: : XE2 Update 4
Duplicate of:  None
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Total Votes: 5
EAccessViolation exception is raised in TMonitor.RemoveWaiter in heavily multi-threaded applications.

This issue makes TMonitor unusable. It's a show stopper.
Steps to Reproduce:
1. Open, compile and run the attached project
2. After 10..100 iterations in the main loop, an EAccessViolation will be raised in TMonitor.RemoveWaiter (system.pas, line 12665)

Reproduced on the following CPUs (Win7 64bit, not VM):
* Intel Core i7 950 (8 cores)
* Intel Core i5 2500 (4 cores)
* Intel Core 2 Duo E6750 (2 cores)
Patch for Delphi XE is available at

Tomohiro Takahashi at 3/4/2012 7:54:35 PM -
Is your issue related to QC#101114 ?

Does your issue still occur with XE2(Trial), which is already Update 4.
I tested your program with Delphi XE2 Update 4(16.0.4429.46931), but I can not reproduce the AV.

Balazs Farkas at 3/5/2012 6:47:28 AM -
I've attached a new test project that reproduces the issue outside of the IDE.

We can't continue development and can't deploy our application because of this issue. I've tried XE2 trial (16.0.4429.46931), it's ok, but we have purchased XE, not XE2. Should we expect a hotfix or a free upgrade to a working version?

Tomohiro Takahashi at 3/6/2012 6:51:06 PM -
> ...  but we have purchased XE, not XE2. Should we expect a hotfix or a free upgrade to a working version?
Could you please contact technical support service or Sales rep of Embarcadero? Sorry for the inconvenience.

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