Date: Wed, 12 Aug 1998 22:06:55 GMT From: loschert@servint.com To: FreeBSD-gnats-submit@FreeBSD.ORG Subject: misc/7600: Pthreads Bug - Interaction between printf and pthread_self Message-ID: <199808122206.WAA00865@test.accucount.com>
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>Number: 7600 >Category: misc >Synopsis: Pthreads Bug - Interaction between printf and pthread_self >Confidential: no >Severity: serious >Priority: medium >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Wed Aug 12 19:10:01 PDT 1998 >Last-Modified: >Originator: Matt Loschert >Organization: ServInt Internet Services >Release: FreeBSD 2.2.7-STABLE i386 >Environment: FreeBSD 2.2.7-STABLE #0: Thu Jul 23 10:04:36 GMT 1998 >Description: While testing a couple of server apps that I had written, I discovered that in certain situations, the process would "run-away". At that point, the app could only be killed with a kill -9 and top would show that the process was eating up 99.9% of the cpu cycles. I found that the condition that instigated the problem was starting the app as a background process and then exiting the shell. Almost immediately after exiting the shell, the process would go haywire. :) The apps use pthreads and therefore -libc_r. I attempted to isolate the problem this evening by stripping out extraneous code. I was able to cut it down to the following program. The line that it does not like is the printf line that calls pthread_self to show the thread id. >How-To-Repeat: 1. Compile the below code with the following command: gcc -Wall -o bug FILENAME.c -lc_r 2. Run the program in the background with: ./bug & 3. Exit the shell. 4. Log back in, check cpu usage with top. ----CODE BEGINS (FILENAME.c)---- #include <stdio.h> #include <unistd.h> #include <pthread.h> void *newthread (void *vptr); int main() { pthread_t thread; pthread_create (&thread, NULL, newthread, NULL); pthread_join (thread, NULL); exit(0); } void *newthread(void *vptr) { for(;;) { printf("Thread %d: Just looped again.\n", (int) pthread_self()); sleep(5); } } ----CODE ENDS---- >Fix: Don't know, hope this helps though. >Audit-Trail: >Unformatted: To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message
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