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From "Todd Lipcon (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-7156) getpwuid_r is not thread-safe on RHEL6
Date Wed, 09 Mar 2011 18:16:59 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-7156?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13004691#comment-13004691
] 

Todd Lipcon commented on HADOOP-7156:
-------------------------------------

I will answer all of your questions and hope you will withdraw your -1:

bq.  Are we going to update this list if Debian/Scientific Linux/Mandriva/... are found to
be non-POSIX compliant?

I will happily volunteer to +1 and commit a patch that anyone should submit to update the
list. Please feel free to do so. The list doesn't claim to be complete, only to provide some
examples of systems where it's the case.

bq. If yes, are we going to push a new Apache release when this list is updated?

No, like any other documentation improvement it should wait for the next release. Our definitive
documentation lives in the source tree. The fact that some of it is in the wiki doesn't change
that.

bq. What does RHEL 6.0 actually mean? If I put a new pam rpm that fixes the issue, am I still
running RHEL 6.0?

I would assume RHEL 6.0 means that you are not installing packages that are not part of the
RHEL 6.0 release. If you went and installed a random RPM that you built from source or some
other vendor, you're no longer running a stock RHEL 6.0. Again, the docs are not meant to
be complete. Assumedly if you've updated your pam manually to workaround this issue, you'd
know that, and you wouldn't turn on the config option!


And, seriously, with the HADOOP-7115 cache in place, this becomes a really rare race condition.
Is it really worth making such a big deal? I'd like to move on to fixing other bugs, please.


> getpwuid_r is not thread-safe on RHEL6
> --------------------------------------
>
>                 Key: HADOOP-7156
>                 URL: https://issues.apache.org/jira/browse/HADOOP-7156
>             Project: Hadoop Common
>          Issue Type: Bug
>    Affects Versions: 0.22.0
>         Environment: RHEL 6.0 "Santiago"
>            Reporter: Todd Lipcon
>            Assignee: Todd Lipcon
>            Priority: Critical
>             Fix For: 0.22.0
>
>         Attachments: hadoop-7156.txt, hadoop-7156.txt, hadoop-7156.txt
>
>
> Due to the following bug in SSSD, functions like getpwuid_r are not thread-safe in RHEL
6.0 if sssd is specified in /etc/nsswitch.conf (as it is by default):
> https://fedorahosted.org/sssd/ticket/640
> This causes many fetch failures in the case that the native libraries are available,
since the SecureIO functions call getpwuid_r as part of fstat. By enabling -Xcheck:jni I get
the following trace on JVM crash:
> *** glibc detected *** /mnt/toolchain/JDK6u20-64bit/bin/java: free(): invalid pointer:
0x0000003575741d23 ***
> ======= Backtrace: =========
> /lib64/libc.so.6[0x3575675676]
> /lib64/libnss_sss.so.2(_nss_sss_getpwuid_r+0x11b)[0x7fe716cb42cb]
> /lib64/libc.so.6(getpwuid_r+0xdd)[0x35756a5dfd]

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