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From: "John William" <jw2357 AT hotmail DOT com>
To: cygwin AT cygwin DOT com
Subject: CYGWIN 1.5.9-1 - Is vprintf() not thread safe?
Date: Sun, 16 May 2004 02:19:16 +0000
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Message-ID: <BAY1-F125a9hoUHAQfN00018dc6@hotmail.com>
X-OriginalArrivalTime: 16 May 2004 02:19:16.0725 (UTC) FILETIME=[301F0A50:01C43AEC]

I'm having problems with a program that uses vprintf() to show error 
messages. The program works fine when run as a single-threaded program. When 
compiled as a multi-threaded program, the console output of vprintf() is 
"interleaved" with output from the various threads mixed together. With a 
large number of threads, the program often drops core.

Adding a pthread_mutex_lock() and ..._unlock() pair around the vprintf() 
makes it work correctly and it no longer drops core.

From reading the GNU docs, I had the impression that functions such as 
vprintf() were supposed to be thread safe. I have noticed that printf() also 
appears to not be thread-safe, but I haven't methodically checked all the 
related functions.

Please cc: any replies to me by e-mail as I am not subscribed to the list. 
Thank you in advance for any help that can be offered.

- John

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