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Posted to yarn-issues@hadoop.apache.org by "Hitesh Shah (JIRA)" <ji...@apache.org> on 2013/02/20 20:53:13 UTC
[jira] [Updated] (YARN-100) container-executor should deal with
stdout, stderr better
[ https://issues.apache.org/jira/browse/YARN-100?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Hitesh Shah updated YARN-100:
-----------------------------
Labels: usability (was: )
> container-executor should deal with stdout, stderr better
> ---------------------------------------------------------
>
> Key: YARN-100
> URL: https://issues.apache.org/jira/browse/YARN-100
> Project: Hadoop YARN
> Issue Type: Bug
> Components: nodemanager
> Affects Versions: 2.0.1-alpha
> Reporter: Colin Patrick McCabe
> Priority: Minor
> Labels: usability
>
> container-executor.c contains the following code:
> {code}
> fclose(stdin);
> fflush(LOGFILE);
> if (LOGFILE != stdout) {
> fclose(stdout);
> }
> if (ERRORFILE != stderr) {
> fclose(stderr);
> }
> if (chdir(primary_app_dir) != 0) {
> fprintf(LOGFILE, "Failed to chdir to app dir - %s\n", strerror(errno));
> return -1;
> }
> execvp(args[0], args);
> {code}
> Whenever you open a new file descriptor, its number is the lowest available number. So if {{stdout}} (fd number 1) has been closed, and you do open("/my/important/file"), you'll get assigned file descriptor 1. This means that any printf statements in the program will be now printing to /my/important/file. Oops!
> The correct way to get rid of stdin, stdout, or stderr is not to close them, but to make them point to /dev/null. {{dup2}} can be used for this purpose.
> It looks like LOGFILE and ERRORFILE are always set to stdout and stderr at the moment. However, this is a latent bug that should be fixed in case these are ever made configurable (which seems to have been the intent).
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