I'm using the Posix's mutexes in a project. I have 3 threads and 3 queues. The problem is: I used the mutexes to "protect" the access to the queues. But the first started thread monopolizes the use of the queues. See a example code:
[Code].....
I'm a bit worried about "too many mutexes" in my little curses-based app and would like to get confirmation/opinions that I'm doing this right. I've got an array: int nums[60] I've got 61 threads. 1-60 are doing math on the value in their array index (ie: thread1 increments nums[1], threadN increments nums[N]), then sleep(1) The 61st thread is my curses thread which does a for-loop over the array and prints out all the values to the screen, then sleep(1)
Right now, I've got 1 mutex which gets locked/unlocked each time one of the 60 threads needs to update its array-index with a new value, and the 61st thread locks the same mutex just before the for-loop beings reading the values and unlocks after ending the loop.
My questions:
A) Does the above seem OK? (I know it's ok, cause everything works right now but would like opinions on it)
B) Do I even need the mutexes since 1-60 only ever update their own index and 61 just reads?
C) If I do need the mutex protection, is there a better, more efficient way?
I am implementing an IPC mechanism using message queues (Sys V).I can receive the messages using msgrcv() function. I am wondering how can I listen on the new messages. I would like to implement a mechanism that would notify me when there is a new message in the queue for me and I will call the msgrcv() function to retrieve the message.
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int main()
{
FILE *fp;
fp = fopen ("mytest.txt","wb");
if (NULL == fp)
{
[Code]....
I have installed OpenSuse 11.3 32 Bit in a virtual machine on an older computer on a Windows XP host and on a new computer with AMD Phenom II X4 965 processor.
With sysbench I tested the performance of mutex and on the new computer it is 3 - 4 times slower than on the virtual machine. Other performance tests with sysbench for CPU, memory and threads are faster on new computer like expected. I tested this, because I have a slower performance of table creation in MySql tested with sql-bench, where creation of 10000 tables lasts 45 seconds on the virtual machine but over 400 seconds on the new computer.
I have tested with kernel-desktop and kernel-default but there are not large differences. File creation was tested with bonnie++ and is on newer computer faster as expected.
My questions are:
- Why is the mutex handling on the multi core CPU slower than in the virtual machine and how to speed up this?
- Or is there another reason why table creation of MySql is so much slower on multi core CPU?
Anyone know of the simple (!) command syntax to : a) download the full SQF tree from [URl].. b) maintain that tree WITHOUT having to download the whole dang thing again.
I'm 100% certain this is possible - that's exactly what source-code repository tools like subversion and git are supposed to do. But Git is complex and that site doesn't seem to have an obvious (to me) method of doing part b)
I have an Ubuntu Server running CUPS-PDF successfully. The problem that I am running into now is that we want to have different CUPS-PDF queues.Example:Joe from Finance wants his PDF prints to go to /home/finance which is samba shared out to all users in Finance. Mark from Operations needs logs printed out to /home/ops which is samba shared to all users in Operations and must be landscape.Finance and Operations print from the command line (lp -d print-queue filename) on the server via ssh since their app runs from a terminal.
I have looked and looked all over the net and through the cups-pdf documentation to see if there is a way to force the URI for the cups-pdf print queue instead of it going to the default of $HOME/Desktop as stated in my /etc/cups/cups-pdf.conf file. Basically, I want to set up a cups pdf printer called Finance, Advert and Ops that has all the options they need so when they print something from the linux applications, and they tell it to print to the virtual printer that they have permission to use and it go to the respective directory that they have access too.
I am trying to set up a print server here on a Squeeze system using the stock debian CUPS package. It seems that since Apple has bought this package, it has caused me nothing but grief. I have set up two different USB printers with raw print queues, and every time I send a print job to either of them, the job disappears into thin air, with no error output. In fact, when I look at the queue, it says the job was completed successfully. I look at the logs, and there is no output indicating any issues. Just for kicks, I reconfigured one of the printers to use a linux driver, and it printed just fine (a little slow, but fine). I set it back to raw, and the jobs disappear again into oblivion.
I have done this many times in the past, and never had any issues -- I even had this very same printer set up that way about a year ago, and it worked great. The only noteworthy thing that seems to have changed is that there are no longer any files called "mime.types" and "mime.convs". It seems they have been replaced by "raw.types" and "raw.convs". The contents of these two files are as follows:
raw.types: application/octet-stream
I have a fairly standard Exim setup for inbound and outbound mail. Recently our development team has put together a PHP app that allows us to send out bulk mails to our clients. The PHP app uses standard PEAR libraries to initiate an SMTP connection to localhost (application and mail server are on the same box). The idea here is that the application will send out roughly 10'000 emails in a very short time period (60 seconds or so) which Exim will then hold in its queue for delivery.
The problem comes in where after about 50 emails, Exim stops accepting mail and loggs the following error in the exim_main.log file: SMTP command timeout on connection from localhost [127.0.0.1] Could it be that this is because Exim immediately starts delivering the mail and then stops accepting new incoming connections? I thought that increasing the SMTP limits may be the problem here, but even after setting new values in the exim.conf file to the following, I still get the same problem:
queue_run_max = 5000
smtp_accept_max = 5000
smtp_accept_queue = 5000
This begs two questions: How do I resolve this? What is the best way for configuring Exim to accept a huge amount of mail into the queue in a very short time period, but then gradually delivery it once it's all in the queue? I've seen some people run separate Exim daemons for incoming and outgoing mail; is this a good solution?
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View 2 Replies View Relatedrecently I am interesting at apparmor, and I have read some docs of it, but I have a question that how to protect apparmor itself? I mean only if gained root privilege then stop apparmor service, all the protection will no longer effect, if I hiding or remove root user then how to remodify profiles if needed that because have not enough privilege.
Is there apparmor maillist? maybe you can email me: <email removed for obvious reasons>
I would like to know how to protect networks against VPN attacks? How does big industries do it? What does the government tend to use? Are any tools open source that I may get?
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this file is located in the same folder that I want to protect. code...
How can I protect a pdf from from print or copy?
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