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Subj : Re: I write a multithread program with pthread, and meet a program
To   : comp.programming.threads
From : Giancarlo Niccolai
Date : Mon Apr 18 2005 11:42 am

Loic Domaigne wrote:

> Hello,
> 
>> But I am still surprised that the new thread can not be stopped
>> correctly.
> 
> You still didn't told us which Pthreads implementation you are using.
> LinuxThreads or NPTL?
> 
> Does the effect subsists when doing the following export before running
> the program?
> bash$ export LD_ASSUME_KERNEL=2.4.19
> 
>> cout may be a cancellation point or not.
>> Theoritically, if cout is not a cancellation point, the new thread will
>> continue to run when the main thread call pthread_cancel(); if it is
>> cancellation point, the new thread will be stopped.
>> But as a matter of fact, the new thread does not run and is not
>> stopped. In linux, the new thread will be a zombie.
>> What I want to know is why.
> 
> It's only a theory at that point... But it looks like a bug in the
> libstdc++ or the libpthread, when a thread is being cancelled while
> writting on cout.
> 

Uhm, AFAIK write() system call is a cancellation point, and cout << is
supposed to write somewhere. So it *ought* to be a cancellation point
unless posix or c++ standards states otherwise. There is not any statement
in this sense to may knowledge, but I may be outdated...

Giancarlo Niccolai.

.

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