Interrupted System Call Error 4
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Python Select Interrupted System Call
Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community ioerror: [errno 4] interrupted function call of 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up What is the proper way to handle (in python) IOError: [Errno 4] Interrupted system call, raised python eintr by multiprocessing.Queue.get up vote 9 down vote favorite When I use multiprocessing.Queue.get I sometimes get an exception due to EINTR. I know definitely that sometimes this happens for no good reason (I open another pane in a tmux buffr), and in such a case I would want to continue working and retry the operation. I can imagine that in some other cases The error would be due to a good reason
Python Catch Interrupted System Call
and I should stop running or fix some error. How can I distinguish the two? Thanks in advance python error-handling queue multiprocessing ioerror share|improve this question asked Jan 3 '13 at 9:36 Shwouchk 9028 you should make sure the queue is not empty before get: if not queue.empty(): queue.get() –Inbar Rose Jan 3 '13 at 9:39 I believe that if the queue is empty, it will just block the call. Won't it? In any I don't think this is the cause of the error. –Shwouchk Jan 3 '13 at 10:26 add a comment| 2 Answers 2 active oldest votes up vote 11 down vote accepted The EINTR error can be returned from many system calls when the application receives a signal while waiting for other input. Typically these signals can be quite benign and already handled by Python, but the underlying system call still ends up being interrupted. When doing C/C++ coding this is one reason why you can't entirely rely on functions like sleep(). The Python libraries sometimes handle this error code internally, but obviously in this case they're not. You might be interested to read this thread which discusses this problem. The general approach to EINTR is to simply handle the error and retry the op
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more python ioerror about hiring developers or posting ads with us Stack Overflow Questions Jobs Documentation Tags Users python signal Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up Catching / blocking SIGINT during system call up vote 7 down vote favorite 2 I've written a web crawler that I'd like to be able to stop via http://stackoverflow.com/questions/14136195/what-is-the-proper-way-to-handle-in-python-ioerror-errno-4-interrupted-syst the keyboard. I don't want the program to die when I interrupt it; it needs to flush its data to disk first. I also don't want to catch KeyboardInterruptedException, because the persistent data could be in an inconsistent state. My current solution is to define a signal handler that catches SIGINT and sets a flag; each iteration of the main loop checks this flag before processing the next url. However, I've found that if the system happens http://stackoverflow.com/questions/3016369/catching-blocking-sigint-during-system-call to be executing socket.recv() when I send the interrupt, I get this: ^C Interrupted; stopping... // indicates my interrupt handler ran Traceback (most recent call last): File "crawler_test.py", line 154, in
closed defect (fixed) error: (4, 'Interrupted system call') the known problem Reported by: nk Owned by: liori Priority: https://trac.gajim.org/ticket/674 low Milestone: 0.4 Component: chat Version: 0.4.1 Severity: normal Keywords: Cc: liori@…, gjc@… Blocked By: Blocking: OS: Description Traceback (most recent http://poincare.matf.bg.ac.rs/~ivana/courses/tos/sistemi_knjige/pomocno/apue/APUE/0201433079/ch10lev1sec5.html call last): File "/home/kirov/Projects/gajim/src/common/connection.py", line 1909, in process self.connection.Process(timeout) File "/home/kirov/Projects/gajim/src/common/xmpp/dispatcher.py", line 112, in Process if self._owner.Connection.pending_data(timeout): File "/home/kirov/Projects/gajim/src/common/xmpp/transports.py", line 155, in interrupted system pending_data return select.select([self._sock],[],[],timeout)[0] error: (4, 'Interrupted system call') Attachments (3) gajim-674-1.patch (1.7 KB) - added by Liorithiel 11 years ago. gajim-eintr3.diff (2.6 KB) - added by gjc 11 years ago. EINTR handling, take 3 gajim-sigpipe.diff (1.7 KB) - added by gjc 11 years ago. interrupted system call Add SA_RESTART option to SIGPIPE signal action Download all attachments as: .zip Oldest first Newest first Threaded Comments only Change History (43) Changed 11 years ago by Liorithiel Attachment gajim-674-1.patch added comment:1 Changed 11 years ago by Liorithiel Cc liori@… added This patch works for me... at least now. comment:2 Changed 11 years ago by nk Owner changed from dkirov to liori bmalkow who has this problem almost everytime (after he applied this patch): 1. I select 'online' 2. I see that gajim connect to server and receive roster 3. when all(?) roster positions are readed, then gajim throws this error: Traceback (most recent call last): File "/tmp/gajim-0.9/src/common/connection.py", line 2081, in process self.connection.Process(timeout) File "/tmp/gajim-0.9/src/common/xmpp/dispatcher.py", line 120, in Process self.Stream.Parse(data) File "/tmp/gajim-0.9/src/common/xmpp/simplexml.py", line 336, in endtag self.dispatch(self._mini_dom) File "/tmp/gajim-0.9/
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 blocked system call. Here, we have to differentiate between a system call and a 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 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 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 ve