Sponsored Content
Top Forums Programming In unix how we can test or check race condition in c program by using multi threads Post 302291240 by redoubtable on Wednesday 25th of February 2009 04:05:50 AM
Old 02-25-2009
How are you creating the race condition?

You can easily prevent race conditions by creating a temporary file and using rename() to replace the file after checking the timestamp of the original file.

If only your program is changing the file, you can also use flock(fd, LOCK_EX) so that if another instance of your program also uses flock() it will block until the other instance finishes processing or calls flock(fd, LOCK_UN).

Keep in mind that flock() doesn't prevent file unlink()ing.
 

9 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

race condition with wait() function

Hi, I'm currently writing a bash script, that starts multiple threads: ____________________ #!/bin/bash loop=0 while((loop!=10)) do thread & ((loop++)) done #wait for all sub-processes (thread) to finish wait ___________________ Now I want to know, what happens, if a... (2 Replies)
Discussion started by: tho99
2 Replies

2. Linux

In unix how we can test or check race condition in c program by using multi threads

In unix how we can test or check race condition in any c program by using multi thread programming (1 Reply)
Discussion started by: afroze
1 Replies

3. UNIX for Dummies Questions & Answers

In unix how we can test or check race condition in a c program by using multi threads

In unix how we can test or check race condition in any c program by using multi thread programming (1 Reply)
Discussion started by: afroze
1 Replies

4. Programming

In unix how we can test or check race condition in a c program by using multi threads

In unix how we can test or check race condition in any c program by using multi thread programming (1 Reply)
Discussion started by: afroze
1 Replies

5. Programming

Race condition with PTY

I've been experimenting with pseudo-terminals and found something I don't quite understand. Writing an EOF character to the master end doesn't work quite as I expect. Once I've written any other data, the master pty seems to treat a single ^D as a seperator, i.e. writing "abcabc" would let cat do... (1 Reply)
Discussion started by: Corona688
1 Replies

6. Shell Programming and Scripting

How to check weather a string is like test* or test* ot *test* in if condition

How to check weather a string is like test* or test* ot *test* in if condition (5 Replies)
Discussion started by: johnjerome
5 Replies

7. Programming

problem about race condition

Hi all, i'm reading Andrew S.Tanenbaum's book --- Modern Operating System.At the part of discussing race condition.And the author gives a solution with using the TSL instruction,say that one process must call the enter_region function before entering the critical regions and call the leave_region... (0 Replies)
Discussion started by: homeboy
0 Replies

8. Shell Programming and Scripting

Shell script that check the argument passed to it and prints error if test condition is not met

I want to make a script that check for the argument passed to it and generates an error in case any character/string argument passed to it. I am using below code, but its not working. can anyone help. #!/bin/bash if ]; then echo 'An integer argument is passed to the script hence... (3 Replies)
Discussion started by: mukulverma2408
3 Replies

9. Shell Programming and Scripting

if condition to check the hostname (unix)

I want to know the if condition in checking the hostname in unix and then running a cron job (all in a single line) Thanks (2 Replies)
Discussion started by: prash358
2 Replies
FLOCK(1)							  H. Peter Anvin							  FLOCK(1)

NAME
flock - Manage locks from shell scripts SYNOPSIS
flock [-sxon] [-w timeout] lockfile [-c] command... flock [-sxon] [-w timeout] lockdir [-c] command... flock [-sxun] [-w timeout] fd DESCRIPTION
This utility manages flock(2) locks from within shell scripts or the command line. The first and second forms wraps the lock around the executing a command, in a manner similar to su(1) or newgrp(1). It locks a specified file or directory, which is created (assuming appropriate permissions), if it does not already exist. The third form is convenient inside shell scripts, and is usually used the following manner: ( flock -s 200 # ... commands executed under lock ... ) 200>/var/lock/mylockfile The mode used to open the file doesn't matter to flock; using > or >> allows the lockfile to be created if it does not already exist, how- ever, write permission is required; using < requires that the file already exists but only read permission is required. By default, if the lock cannot be immediately acquired, flock waits until the lock is available. OPTIONS
-s, --shared Obtain a shared lock, sometimes called a read lock. -x, -e, --exclusive Obtain an exclusive lock, sometimes called a write lock. This is the default. -u, --unlock Drop a lock. This is usually not required, since a lock is automatically dropped when the file is closed. However, it may be required in special cases, for example if the enclosed command group may have forked a background process which should not be hold- ing the lock. -n, --nb, --nonblock Fail (with an exit code of 1) rather than wait if the lock cannot be immediately acquired. -w, --wait, --timeout seconds Fail (with an exit code of 1) if the lock cannot be acquired within seconds seconds. Decimal fractional values are allowed. -o, --close Close the file descriptor on which the lock is held before executing command. This is useful if command spawns a child process which should not be hold ing the lock. -c, --command command Pass a single command to the shell with -c. -h, --help Print a help message. AUTHOR
Written by H. Peter Anvin <hpa@zytor.com>. COPYRIGHT
Copyright (C) 2003-2006 H. Peter Anvin. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICU- LAR PURPOSE. SEE ALSO
flock(2) AVAILABILITY
The flock command is part of the util-linux-ng package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/. flock utility 4 Feb 2006 FLOCK(1)
All times are GMT -4. The time now is 05:51 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy