This article discuss about java Thread Synchronization. with Practical example.When multiple threads are accessing a common method through their run methods, the output of that particular program is unpredictable, because while one thread is gone half way through the common method, another thread would gain the common method.
Hi guys and girls :)
I have some problem with folder synchronization.
I have a hudson job that make special build from svn data (check outing full project every time), after build folder is synchronized with second folder lets call them build and destination :)
Currently I'm copying build to... (1 Reply)
I want to do a synchronization from local to ftp.
local:
name modified time
a.txt 10:04
c.txt 10:05
ftp:
b.txt 10:00
c.txt 10:05
final result would be
a.txt copy to ftp
b.txt deleted
c.txt nothing to do
Is there a good way to do so?
Thanks. (3 Replies)
Can anybody help me on how to do directory synchronization. i have been reading about rsync and filesync but apparently it seems to me that synchronization is from a source directory to a destination directory only. how about if vice versa - wherein i need to synchronize both directories, updating... (3 Replies)
I have 2 hosts (server and client), on the client side I mount remote directory (through NFS). How can I synchronize content of 2 directories (one on the client, and one on the server, mounted to the client)? i.e. when client is connected to the server synchronization process is automatically... (5 Replies)
i have an HP UNIX box w/c acts as ntp server... I tried to change the time plus 8 minutes... the problem is that the other HP UNIX ntp client did not follow the time... when I tried to restart ntp client... using stop start it only sync to the server once... when I issue the command "ntpq -p", w/c... (2 Replies)
Hello,
J create a thread C with a JNI function via JAVA.
J have the following message (but not in each time):
Someone has an idea ?
Thank.
Unexpected Signal : 4 occurred at PC=0x78C103E0
Function=
Library=(N/A)
NOTE: We are unable to locate the function name... (0 Replies)
All
What is the best way to keep the system clock synchronized? I have looked at ntp and netdate. Is one good over the other? Basically I want to know if what is the most secure way to keep the system clock insync. netdate will require me to open up some port 37... is this safe? ntp also... (1 Reply)
Hi all
Is there an easy way to synchronize the time of a Linux server with another server (Linux or Windows). I need to do this on a daily basis so that my clock does is insync.
Is synchronizing with an eternal server hazardous to the security of the box?
Thanks in advance
KS (2 Replies)
Thread::Semaphore(3pm) Perl Programmers Reference Guide Thread::Semaphore(3pm)NAME
Thread::Semaphore - Thread-safe semaphores
VERSION
This document describes Thread::Semaphore version 2.12
SYNOPSIS
use Thread::Semaphore;
my $s = Thread::Semaphore->new();
$s->down(); # Also known as the semaphore P operation.
# The guarded section is here
$s->up(); # Also known as the semaphore V operation.
# Decrement the semaphore only if it would immediately succeed.
if ($s->down_nb()) {
# The guarded section is here
$s->up();
}
# Forcefully decrement the semaphore even if its count goes below 0.
$s->down_force();
# The default value for semaphore operations is 1
my $s = Thread::Semaphore->new($initial_value);
$s->down($down_value);
$s->up($up_value);
if ($s->down_nb($down_value)) {
...
$s->up($up_value);
}
$s->down_force($down_value);
DESCRIPTION
Semaphores provide a mechanism to regulate access to resources. Unlike locks, semaphores aren't tied to particular scalars, and so may be
used to control access to anything you care to use them for.
Semaphores don't limit their values to zero and one, so they can be used to control access to some resource that there may be more than one
of (e.g., filehandles). Increment and decrement amounts aren't fixed at one either, so threads can reserve or return multiple resources at
once.
METHODS
->new()
->new(NUMBER)
"new" creates a new semaphore, and initializes its count to the specified number (which must be an integer). If no number is
specified, the semaphore's count defaults to 1.
->down()
->down(NUMBER)
The "down" method decreases the semaphore's count by the specified number (which must be an integer >= 1), or by one if no number
is specified.
If the semaphore's count would drop below zero, this method will block until such time as the semaphore's count is greater than or
equal to the amount you're "down"ing the semaphore's count by.
This is the semaphore "P operation" (the name derives from the Dutch word "pak", which means "capture" -- the semaphore operations
were named by the late Dijkstra, who was Dutch).
->down_nb()
->down_nb(NUMBER)
The "down_nb" method attempts to decrease the semaphore's count by the specified number (which must be an integer >= 1), or by one
if no number is specified.
If the semaphore's count would drop below zero, this method will return false, and the semaphore's count remains unchanged.
Otherwise, the semaphore's count is decremented and this method returns true.
->down_force()
->down_force(NUMBER)
The "down_force" method decreases the semaphore's count by the specified number (which must be an integer >= 1), or by one if no
number is specified. This method does not block, and may cause the semaphore's count to drop below zero.
->up()
->up(NUMBER)
The "up" method increases the semaphore's count by the number specified (which must be an integer >= 1), or by one if no number is
specified.
This will unblock any thread that is blocked trying to "down" the semaphore if the "up" raises the semaphore's count above the
amount that the "down" is trying to decrement it by. For example, if three threads are blocked trying to "down" a semaphore by
one, and another thread "up"s the semaphore by two, then two of the blocked threads (which two is indeterminate) will become
unblocked.
This is the semaphore "V operation" (the name derives from the Dutch word "vrij", which means "release").
NOTES
Semaphores created by Thread::Semaphore can be used in both threaded and non-threaded applications. This allows you to write modules and
packages that potentially make use of semaphores, and that will function in either environment.
SEE ALSO
Thread::Semaphore Discussion Forum on CPAN: <http://www.cpanforum.com/dist/Thread-Semaphore>
threads, threads::shared
MAINTAINER
Jerry D. Hedden, <jdhedden AT cpan DOT org>
LICENSE
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
perl v5.18.2 2013-11-04 Thread::Semaphore(3pm)