Programming :: Synchronization Between Threads Fails - Resource Unavailable
May 6, 2009
I am working with a C++ program consisting of two threads. The first threads receives packets through an UDP unicast connection and stores them in a buffer. The second thread reads the packets from the buffer and sends them through an UDP multicast connection. Both use blocking sockets and share a common buffer and a linked list L1, which are protected by mutexes. The program seemed to work just fine, receiving a packet and sending it almost immediately, but started giving some trouble recently. The synchronization between both thread started failing, and I decided to use a non-blocking socket in the sending thread. As a consequence, sendto() doesn't work in some cases, causing an errno 11 (Resource unavailable).
[Code] ...
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Mar 7, 2010
I'm working a program to implement a simple multi-process browser. The browser works by having a ROUTER process as the parent of everything else in the program. There's another process called the CONTROLLER which is part of where the user can input information. To tell the ROUTER to make a new tab in the browser the user activates a function from the CONTROLLER to send the create new tab information to the ROUTER:
Code:
void new_tab_created_cb(GtkButton *button, gpointer data)
{
[code]...
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Sep 11, 2009
I installed a while ago two CentOS 5.3 servers. One of them was running Samba and another OpenLDAP. I configured Samba to act as a PDC on the network and everything was working fine. I was already on policies configuration and desktop migrations.
The following problems are Samba server problem, LDAP server is on hold until I figure out the first problem.
Software conf:
Hardware conf:
One day, both servers began crashing, and after a while, it showed the following during the boot on Samba:
After that, ALL CentOS installations had this problem after yum update, epel installation and some smb.conf modifications:
I figured out it might be EPEL (i did installed yum-priorities and tryied updating the base sistem BEFORE epel installations), so I installed the system without EPEL yum repository. After some good and relieving 15 min working, the system crashed AGAIN after yum base update and showed the following on boot time:
And it stops right there.
Maybe some wrong kernel update? the first time it crashed in one way, with running updated system (After the first update, no manual update was done). The sequel problems were all after Kernel update and EPEL. The last one was just after Kernel update. I'll try one last time with NO updates, but i can't run the system like that.
I can't do anything that might one day crash, it's a 6000-7000 user gov environment, but i don't want to install another distro, so if I don't figure it out, they will order me to.
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Mar 25, 2010
I have had ubuntu installed for a few months now and have been loving it. Yesterday I wanted to get JDK installed for a found a forum that said how to install it on ubuntu. The installation was not a success (I am not sure why because I am not skilled when it comes to the command line and I didn't understand the error). Later, I tried to install a different application just through the ubuntu software center and it said it was waiting for a different software manager to finish. I didn't understand what was still running because I had all other applications closed that I know of.
Once I restarted the problem was the same. Then I found a bug where people had the same problem with the software manager and they entered this and fixed it:
sudo dpkg --configure -a Now whenever I try to apt-get anything I get:
E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable)
E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?
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Apr 10, 2010
Today when tried to install a software from the terminal...d command dint work. Check this.
calvin@calvin-desktop:~$ sudo apt-get install pidgin
[sudo] password for calvin:
E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable)
E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?
calvin@calvin-desktop:~$
It says that it cannot get lock! I have installed ubuntu along with windows! and drive E: is in windows.
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Feb 2, 2011
I am running ubuntu 10.04 and am trying to get updates via the update manager but continue to get the following errors:
"E: could not get lock /var/cache/apt/archives/lock - open(11:Resource temporarily unavailable)
E: Unable to lock the download directory"
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Jan 19, 2010
I have a few updates that I can install using the Update Manager but when I click the "Install Updates" button I get this pop up window message
E: Could not get lock /var/cache/apt/archives/lock - open (11: Resource temporarily unavailable)
E: Unable to lock the download directory
How to get the updates?
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Sep 9, 2010
I was just mucking about in xfce, trying out new window buttons in conjunction with the black theme - dusk?? - when POW! - X shut down. Rebooting didn't restore things. Error is along these lines:
xfce4-session: Fatal IO error 11 (Resource temporarily unavailable) on X server :0.0. xfwm4: Fatal IO error 11 (Resource temporarily unavailable) on X server :0.0.
[Code]....
Is there a config file I can edit to get away from the window button setting it dislikes, or is reinstalling xfce the only option?
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Mar 25, 2010
When i connect windows server 2003 from ubuntu these error displayed .When i installing the tsclient, by executing these following command from a Terminal window:
sudo apt-get install tsclient
When i run these command the following error displayed.
E: Could not get lock /var/lib/dpkg/lock - open (11 Resource temporarily unavailable)
E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?
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Jun 12, 2011
I recently installed Ubuntu 11.04 on an old Sony Vaio laptop. I was following some of the steps here..[url]
The step "Enable Full DVD Playback(Dual Layer DVD Support)" did not finish correctly doh and now I can't use 'sudo apt-get' for anything or the software center or using the 'Update Manager' does not work.
The update manger says it may be caused by an update not finishing correctly which sounds correct as explained above. The apt-get command gives me back the following....'Could not get lock /var/lib/dpkg/lock resource temporarily unavailable' 'unable to lock administration directory /var/lib/dpkg is another process using it?'
I tried the obvious restart but that hasn't worked.
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Jun 30, 2010
I've been running Samba on Gentoo as a PDC for a Windows XP domain for several years. We are using the IdealX smbldap tools to maintain users, we are storing accounts in OpenLDAP, and everything has been just golden for quite a while. However, for various reasons, we are migrating our servers away from Gentoo and onto Ubuntu 10.04 (64-bit). Unfortunately, replicating our Samba PDC/OpenLDAP backend on Ubuntu is kicking our backsides.I've got Samba 3.4.7 running. I've got OpenLDAP running. ldapsearch/ldapmodify/ldapadd all work correctly. However, when I try to mount a Samba share on another Ubuntu machine, I get...:
Code:
testuser@testhost:~$ sudo mount.cifs //192.168.4.173/testuser /home/testuser/mnt/testuser --verbose -o
[code]...
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Apr 3, 2010
I have pidgin2.5.2. I want to install pidgin2.6.6.How can I do that?E: Could not get lock /var/lib/dpkg/lock - open (11 Resource temporarily unavailable)E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?
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Jan 4, 2010
I have a machine running on RH with 4G memory and 8G swap.Just now I'm having a problem when loging in with a user - just call it "userX" -.Each time I'm logged in I got a message Code:-bash: fork: ource temporarily unavailableAnd almost everytime I entered any command, it gives me the same warning. In some time (rarely) it will give me proper result, but almost any time it gives me the warning and no result.When I use 'top' command, it shows that I still have 500M free memory and about 8G free swaps. Plus the process for userX is less than 20 processes, and each of them are short processes (less than an hour, mostly just few seconds).As a note this problem only occur on userX, for any other user on the machine everything works just fine.
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Mar 3, 2011
My son's netbook with 10.10 netbook remix failed to boot. Using the Live install CD and Gparted I couldn't repair the EXT4 filesytem. The error reported was:
e2fsck : Device or resource busy while trying to open ...
After trying many solutions and web searching I decided to try a different live CD and tried Knoppix 6.4.4
Using the command interface I typed e2fsck -v -f -y /dev/xxxx (xxxx = your device). This worked first time and the machine rebooted without hesitation.
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Sep 28, 2010
i want a process that can operate as both a TCP echo server and a UDP echo server. The process can provide service to many clients at the same time, but involves a single process that does not start up any other threads.
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Feb 27, 2011
I have two processes that share a piece of memory, and i want to use the shared memory to send data from one process to the other. it's like a simple consumer-producer problem. when the producer fills the shared memory, it waits until the consumer can consume some data in the memory; the consumer needs to wait if there is no data in the memory. The thing gets complicated when both threads are allowed to sleep and wait for the other to wake it up.
i wanted to use condition variable of pthread for synchronization, but it doesn't work in multiple processes. i tried semaphore, but it's quite complicated and i still cannot make it right. I believe it's a common problem and someone should have written similar code before, or maybe the code is even wrapped in a library, but when I search for it on Internet, I only found information about how to share memory between processes. Does anyone know where I can find this kind of code or library?
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Dec 1, 2010
I have two threads & i want to run it continuously ,with while(1) it is possible . Is there any other way to run the threads continuously
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Nov 25, 2010
In all the examples I have found the server accepts the client's conection, proccess the data received and close the socket. In an very schematic way it would be something like:
Code:
client_thread{
select to see if there is data to read from socket fd
if there is something to read{
[code]....
Should I use mutexs or semaphores to block the socket fd before read and write or it is not necesary?
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Dec 29, 2010
How to list all the threads spawned by a process?
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Mar 26, 2011
I wrote a C program using Pthreads to compute the product of 2 matrices. Each element in the product matrix is computed in a separate thread. Eg: Thread (i,j) computes the element C[i][j] of the matrix C, where C=A*B. A is m*n, B is n*p, C is m*p. m,n,p are given as command-line arguments. A and B are initialized to random values from 1 to 10, while all elements of C are initialized to -1.But some threads do not get their arguments (i,j) correctly. So some elements C[i][j] still remain as -1, even after the program is over. My OS is Ubuntu 10.10 (Maverick Meerkat) 32-bit.I ran the program on another computer and it worked correctly. Is it due to a problem in the Pthreads library in my OS? Please help me. I have attached the source code.
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Mar 29, 2011
I have doubt regarding cpu sharing between process and threads.In my program iam creating 4threads=> 1 process+4 threads. How is cpu alloted to these all tasks. Is here process is getting cpu time like thread or having more cpu time than threads.
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Dec 14, 2010
In posix multi threading, how to send thread1 local data to thread2...?
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Nov 26, 2010
Code:
void* thread(void* arg)
{
[code]....
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Mar 15, 2011
I have 2 threads and both of them are deleting memory at the end nedded by both.
My problem is that maybe it can happen that a thread start and finish before the other one starts and so it deletes the memory nedded by the other thread. How can I synchronize them so that this can't happend.
As a design my threads look like this:
Code:
The other thread looks the same, but this isn't unoff to stop thread1 to finish before thread2 starts.
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Jun 14, 2011
I am new to linux and am trying to write a script that will ping IP addresses and say either online or unavailable.
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Feb 17, 2011
Please I want Know the code of the Merge Sort with threads in C
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Jun 8, 2011
IS there any command to see number of threads are running in a process .I have check ps -eLf but it wont show display for all the threads
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Jun 7, 2011
How to communicate between two threads using message queue?
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Jul 21, 2011
Fedora15 32bit. I write a test program, it creates new thread continually, the thread does nothing but sleep. I find virtual memory increases up almost 10Mb when a new thread is created. and when there's more than 200 threads, the virtual memory used by the program is 3Gb, and now cann't create new thread. but on windows, it costs little memory. What can I do to config the operation system to take less memory on threads?
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Jul 25, 2010
I am runig a program on a server at my university that has 4 Dual-Core AMD Opteron(tm) Processor 2210 HE and the O.S. is Linux version 2.6.27.25-78.2.56.fc9.x86_64. My program implements Conways Game of Life and it runs using pthreads and openmp. I timed the parrallel part of the program using the getimeofday() function using 1-8 threads. But the timings don't seem right. I get the biggest time using 1 thread(as expected), then the time gets smaller. But the smallest time i get is when i use 4 threads.
Here is an example when i use an array 1000x1000.
Using 1 thread~9,62 sec, Using 2 Threads~4,73 sec, Using 3 ~ 3.64 sec, Using 4~2.99 sec, Using 5 ~4,19 sec, Using 6~3.84, Using 7~3.34, Using 8~3.12.The above timings are when i use pthreads. When i use openmp the timing are smaller but follow the same pattern.I expected that the time would decrease from 1-8 because of the 4 Dual core cpus? I thought that because there are 4 cpus with 2 cores each, 8 threads could run at the same time. Does it have to do with the operating system that the server runs?
Also i tested the same programs on another server that has 7 Dual-Core AMD Opteron(tm) Processor 8214 and runs Linux version 2.6.18-194.3.1.el5. There the timings i get are what i expected. The timings get smaller starting from 1(the biggest) to 8(smallest excecution time).The program implements the Game of Life correct, both using pthreads and openmp, i just cant figure out why the timings are like the example i posted. So in conclusion, my questions are:
1) The number of threads that can run at the same time on a system depends by the cores of the cpus?it depends only by the cpus although each cpu has more than one cores? It depends by all the previous and the Operating System?
2) Does it have to do with the way i divide the 1000x1000 array to the number of threads? But if i did then the openmp code wouldn't give the same pattern of timings?
3)What is the reason i might get such timmings?
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