Error Interrupted System Call
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Interrupted System Call Errno
4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up TCP sockets, server fails to respond to client, accept: Interrupted system call up vote 0 down vote favorite
Interrupted System Call @ Rb_sysopen
I am trying to implement a TCP server and client in C, running on Solaris. I am new to sockets and am using Beej's Guide as an example. For starters, what I would like is for the client to send a message to the server in the form of word1 word2. Upon receipt, I want the server to extract word2 from the message and send that back to the client. The initial interrupted system call linux client --> server message sending works fine. But the server --> client response is not working. There are several failure symptoms: The server does not appear to even try to send() anything to the client. After receiving the client's message, the server prints: accept: Interrupted system call, then returns to the top of the while(1) loop and remains there until I Ctrl-C out of it. The client's call to recv() returns 0 bytes. I found an old thread here, where the last post says this: accept is being interrupted by the child process sending a signal back to the parent when it terminates (SIGCHLD, if I remember write). You can either ignore SIGCHLD, or you can code accept() to handle the interrupt better (errno is set to EINTR) However, I'm not understanding this. Why is the child process terminating before even attempting the send() portion? What does "handle the interrupt better" mean? After searching some more, I found this question on Stack Overflow: How to handle EINTR (interrupted System Call). I tried adding the code in the accepted answer, replacing write() with send(), but I still see the same behavior. Server code: #include
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Interrupted System Call Python
the company Business Learn more about hiring developers or posting ads with us Stack Overflow interrupted system call fastcgi comm with server Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of interrupted system call (code=4) 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up interrupted system call error when writing to a pipe up vote 1 down vote favorite In my user http://stackoverflow.com/questions/20067657/tcp-sockets-server-fails-to-respond-to-client-accept-interrupted-system-call space Linux application, I have a thread which communicated to the main process through a pipe. Below is the code static void _notify_main(int cond) { int r; int tmp = cond; r = write( _nfy_fd, &tmp, sizeof(tmp) ); ERROR( "write failed: %d. %s\n", r, strerror(r) ); } Pretty straight forward. It's been working fine for quite a while now. But recently, the write call will fail with "interrupted system call" error after the http://stackoverflow.com/questions/5909717/interrupted-system-call-error-when-writing-to-a-pipe programme went under some stress test. Strangely, the stuff actually went through the pipe no problem. Of course I'd still like to go to the bottom of the error message and get rid of it. Thanks, unix pipe signals share|improve this question edited May 6 '11 at 17:51 asked May 6 '11 at 9:56 lang2 2,05922448 add a comment| 2 Answers 2 active oldest votes up vote 1 down vote The write(2) man page mentions: Conforming to SVr4, 4.3BSD, POSIX.1-2001. Under SVr4 a write may be interrupted and return EINTR at any point, not just before any data is written. I guess you were just lucky that it didn't occur so far. If you google just for the "interrupted system call", you will find this thread which tells you to use siginterrupt() to auto-restart the write call. share|improve this answer answered May 6 '11 at 10:10 blubb 4,49011752 thanks. As I added in the original question, it's happening on every write(), which is very strange. –lang2 May 6 '11 at 10:43 @lang2: I assume the writes are enormeously large in the stress tests. Maybe you should try to chunk the data into buffers of a reasonable size and then write these buffers. –blubb May 6 '11 at 10:47 add a comment|
errno was set to EINTR. This was done under the assumption that since a signal occurred and the process caught it, there is a good chance that something has happened that should wake up the http://poincare.matf.bg.ac.rs/~ivana/courses/tos/sistemi_knjige/pomocno/apue/APUE/0201433079/ch10lev1sec5.html blocked system call. Here, we have to differentiate between a system call and a https://groups.google.com/a/soe.ucsc.edu/d/topic/genome/rPPCDeIF_Jg function. It is a system call within the kernel that is interrupted when a signal is caught. To support this feature, the system calls are divided into two categories: the "slow" system calls and all the others. The slow system calls are those that can block forever. Included in this category are Reads that can block the caller forever interrupted system if data isn't present with certain file types (pipes, terminal devices, and network devices)Writes that can block the caller forever if the data can't be accepted immediately by these same file typesOpens that block until some condition occurs on certain file types (such as an open of a terminal device that waits until an attached modem answers the phone)The pause function (which by definition puts the calling process to sleep until a signal is interrupted system call caught) and the wait functionCertain ioctl operationsSome of the interprocess communication functions (Chapter 15) The notable exception to these slow system calls is anything related to disk I/O. Although a read or a write of a disk file can block the caller temporarily (while the disk driver queues the request and then the request is executed), unless a hardware error occurs, the I/O operation always returns and unblocks the caller quickly. One condition that is handled by interrupted system calls, for example, is when a process initiates a read from a terminal device and the user at the terminal walks away from the terminal for an extended period. In this example, the process could be blocked for hours or days and would remain so unless the system was taken down. POSIX.1 semantics for interrupted reads and writes changed with the 2001 version of the standard. Earlier versions gave implementations a choice for how to deal with reads and writes that have processed partial amounts of data. If read has received and transferred data to an application's buffer, but has not yet received all that the application requested and is then interrupted, the operating system could either fail the system call with errno set to EINTR or allow the system call to succeed, returning the partial amount of data received. Si
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