I've been out of the game for a while with C++ but as I read your post, I was reminded of some classes I wrote to manage multiple threads. Also, Bartosz Milewski of Reliable Software - Creators of the distributed version control system, Code Co-op wrote a really cool critical section class wrapper that totally protects against accidentally leaving a lock in place. His discussion of how resource management is the key to reliable message driven software was well done and he had numerous ways to protect against leaving resources open or laying around that would cause memory leaks or hangs. Here it is:
:confused:
Hi!
I have created a Multhreaded Application in Pro*C (using pthreads) with about 5 Threads running simultaneously. The Application is basically to Update a Centralized Table in Oracle, which updates different rows in the Table (Each Thread updates different rows!). The... (16 Replies)
Hi
I need to insert 1million records into MySQL database, but it is taking lot of time as there is no bulk insert support.
I want to spawn 10 processes which will insert 100k records each parallely.
Can somebody help me with a example program to execute this task through shell scripting. (5 Replies)
Situation:
i have multiple pthread_create calls like this:
pthread_create(...., ThreadFunc1,.....);
pthread_create(...., ThreadFunc2,.....);
.
.
which i am using to create multiple threads.All the "ThreadFunc<i>" functions are actually calling same function "Receive" of a class using same... (3 Replies)
hello to all
i want to use multithreading to my UDP broadcast server client program. will anyone help me by proving C code. i am working in fedora. also my requirement is POSIX compliance.please help me..... (0 Replies)
hello to all
i want to use multithreading to my UDP broadcast server client program. will anyone help me by proving C code. i am working in fedora. also my requirement is POSIX compliance.please help me..... (6 Replies)
Dear all,
I am having a huge XML file, as below structure
<EMPLOYEE>
<RECORD id =aaa>
<Salary>99999</Salary>
<section>ssss</section>
</RECORD>
<RECORD id =bbb>
<Salary>77777</Salary>
<section>ssss</section>
</RECORD>
</EMPLOYEE>
This is a 50 GB file I want to read this file in... (9 Replies)
I take this question of the The Linux Programming Interface: A Linux and Unix System Programming page 652 exercise 30.1
I want someone to explain the under line statement because it sounds complex to me couldn't understand anything
30-1 Modify the program (thread_incr.c) so that each loop in... (3 Replies)
Discussion started by: fwrlfo
3 Replies
LEARN ABOUT DEBIAN
ns_csenter
Ns_CritSec(3aolserver) AOLserver Library Procedures Ns_CritSec(3aolserver)__________________________________________________________________________________________________________________________________________________NAME
, Ns_CsDestroy, Ns_CsEnter, Ns_CsInit, Ns_CsLeave - Manage and use critical section locks
SYNOPSIS
#include "ns.h"
void
Ns_CsDestroy(Ns_Cs *csPtr)
void
Ns_CsEnter(Ns_Cs *csPtr)
void
Ns_CsInit(Ns_Cs *csPtr)
void
Ns_CsLeave(Ns_Cs *csPtr)
_________________________________________________________________DESCRIPTION
Critical section locks are used to prevent more than one thread from executing a specific section of code at one time. They are implemented
as "objects", which simply means that memory is allocated to hold the lock state. They can also be called "sychronization objects".
While a thread is executing a critical section of code, all other threads that want to execute that same section of code must wait until
the lock surrounding that critical section has been released.
This is crucial to prevent race conditions which could put the server into an unknown state. For example, if a section of code frees a
pointer and then decrements a counter that stores how many pointers exist, it is possible that the counter value and the actual number of
pointers may be different. If another section of the server relies on this counter and reads it when the pointer has been freed, but the
counter has not yet been decremented, it could crash the server or put it into an unknown state.
Critical section locks should be used sparingly as they will adversely impact the performance of the server or module. They essentially
cause the section of code they enclose into behaving in a single-threaded manner. If a critical section executes slowly or blocks, other
threads that must execute that section of code will begin to block as well until the critical section lock is released.
You will normally want to wrap sections of code that are used to both read and write values, create and destroy pointers and structures or
otherwise look at or modify data in the system. Use the same named lock for both read and write operations on the same data.
Threads that are waiting for a critical section lock to be released do not have to poll the lock. The critical section lock functions use
thread condition functions to signal when a lock is released.
Ns_CsDestroy(csPtr)
Destroy a critical section object. Note that you would almost never need to call this function as synchronization objects are typi-
cally created at startup and exist until the server exits.
The underlying objects in the critical section are destroyed and the critical section memory returned to the heap.
Ns_CsEnter(csPtr)
Lock a critical section object, initializing it first if needed. If the critical section is in use by another thread, the calling
thread will block until it is no longer so.
Note that critical sections are recursive and must be exited the same number of times as they were entered.
Ns_CsInit(csPtr)
Initialize a critical section object. Memory will be allocated to hold the object's state.
Ns_CsLeave(csPtr)
Unlock a critical section once. A count of threads waiting to enter the critical section is kept, and a condition is signaled if
this is the final unlock of the critical section so that other threads may enter the critical section.
SEE ALSO nsd(1), info(n), Ns_MasterLock(3), Ns_MasterUnlock(3), Ns_CondDestroy(3), Ns_CondSignal(3), Ns_CondWait(3), Ns_MutexLock(3), Ns_MutexUn-
lock(3)KEYWORDS AOLserver 4.0 Ns_CritSec(3aolserver)