Login or Register to Ask a Question and Join Our Community


UNIX for Advanced & Expert Users

Issues with select system call

Login to Discuss or Reply to this Discussion in Our Community

 
Thread Tools Search this Thread
Top Forums UNIX for Advanced & Expert Users Issues with select system call
# 1  
Old 04-12-2013
Issues with select system call
1. We are using client-server model communication using TCP/IP protocol

2. The TCP socket created with O_NON_BLOCK flag

3. When we make attempt to send large data to other process, the send is partially successful. It means we attempt to send 90K data, OS sent only 40K data successfully.

4. When we make attempt to send the remaining data, the send call returned immediately with EWOULDBLOCK error

5. After that we are using "select" call for checking the write operation status on the same TCP endpoint.

6. Somehow, some times the select call is not telling us that the socket is ready for write operation (even though the peer process received all the data of all previous send calls)

7. The issue wont happen every time, it happens only once in while.

8. Since select call is not telling me that socket is ready for write operation, I am no doing any write operations and that is leading me to issues.

Your valuable suggestions are welcome.

Thanks,
Masthan
# 2  
Old 04-12-2013
What is your system?

What is your code?
# 3  
Old 04-12-2013
My system is LINUX and my code is "C" programming
# 4  
Old 04-15-2013
Yes, I know you are using C, but actually seeing your code would be more useful than knowing C is the language. Select is something that's occasionally tricky to get just right.

I believe there was a version of the linux kernel that had this bug, though. What version of the kernel are you running?
Code:
cat /proc/version

Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. Homework & Coursework Questions

program to send messages to parent using pipes and select system call

Write a program using select, which will create some number of child processes that continuously send text messages to the parent process using pipes. Each child has its own pipe that it uses to communicate with the parent. The parent uses select () to decide what pipes should be processed to... (1 Reply)
Discussion started by: ripssingh
1 Replies

2. Shell Programming and Scripting

system call

Trying to figure out a load issue with a webserver. I have traced a php script and noticed the following connect(4, {sa_family=AF_INET, sin_port=htons(3306), sin_addr=inet_addr("XX.XX.XX.XX")}, 16) = -1 EINPROGRESS (Operation now in progress) <0.000035> poll(, 1, 2000) = 1 () <0.000120>... (5 Replies)
Discussion started by: rajan007
5 Replies

3. Programming

need help with system call

hi everyone i wrote a system call and compiled the kernel succesfully... my system call is in a file in the kernel folder named my_syscall1.c (kernel/my_syscall1.c) the header file for this system call i added it in the folder include like this include/my_syscall1/my_syscall1.h my problem is... (2 Replies)
Discussion started by: demis87
2 Replies

4. Programming

system call

I have a cgi script which is called after certain time interval, which has this: system ("ls -l /tmp/cgic* | grep -v \"cgicsave.env\" | awk '{print $5}'"); During the execution of this script,the output is 0 sometimes. But due to this the system call is not working at all and doesnt o/p... (2 Replies)
Discussion started by: xs2punit
2 Replies

5. Programming

select() system call takes longer than the timeout specified

Below is my code. Every once in a while the select call takes as long as 150 seconds (discovered by printing time before and after this statement) while the timeout specified into it is only 1 second. Any clue why? I can't believe that select call which has been around for centuries can have a bug,... (15 Replies)
Discussion started by: old_as_a_fossil
15 Replies

6. Programming

Having some trouble with select() call in C

I have this while loop: while (notdone) { //Set the timers waitd.tv_sec = 5; waitd.tv_usec = 0; FD_ZERO(&tempreadfds); FD_ZERO(&tempwritefds); FD_ZERO(&readfds); /* initialize the read fd set */ FD_ZERO(&writefds); /* initialize the write fd set */ ... (1 Reply)
Discussion started by: Legend986
1 Replies

7. Programming

C:system call

Hi I'm studing the system call. I've written a small program that return the time spent in doing some operations. Now I'd like to write one that return the time spent in user mode of a process. I'm reading that i should use the tms struct: clock_t times(struct tms *buf); struct tms {... (2 Replies)
Discussion started by: Dedalus
2 Replies

8. UNIX for Advanced & Expert Users

how to use exceptfds argument in select system call

Hi, Can any one tell me how to use the fourth argument of select system call.I saw example "port forwarding" on the net,but it was too complex for me to understand.Can any one explain me about the usage of exceptfds argument of select system call with simple example. Thanks. (2 Replies)
Discussion started by: bvijaya
2 Replies

9. Programming

c system call

How the c compiler differentiates the system calls and function calls? (1 Reply)
Discussion started by: rangaswamy
1 Replies

10. UNIX for Advanced & Expert Users

how to differentiate system call from library call

Hi, Ho do I differentiate system call from library call? for example if I am using chmod , how do I find out if it is a system call or library call? Thanks Muru (2 Replies)
Discussion started by: muru
2 Replies
Login or Register to Ask a Question