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https://issues.apache.org/jira/browse/HADOOP-10527?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13977538#comment-13977538
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Kihwal Lee commented on HADOOP-10527:
-------------------------------------
> This doesn't seem like what you intended.
Rearranged the code. Since the terminal condition of the loop has changed (no
more fixed limit on # of iterations), I moved realloc() back to after the
sys/lib calls. Compared to pre-HADOOP-10522, it uses single loop instead of
nested loop and return code/error handling was modified.
> Also, please remove the comments about errno not being thread-safe.
They were removed in the previous patch. For a second, I though I screwed up
and posted an old patch again!
Here is something new about this patch.
I thought about what the reasonable initial buffer size and the limit would be.
For user lookups, the buffer can be relatively small and
{{_SC_GETPW_R_SIZE_MAX}} won't be too big. So the max buffer size here will
mostly be for avoiding infinite lookup loop caused by a bug in library. I
think 32KB is far more than enough for containing a single user's passwd entry.
So I set the buffer size limit to 32KB. I did not change the initial buffer
size as {{_SC_GETPW_R_SIZE_MAX}} won't be excessively big and using it as the
initial buffer size will avoid realloc() in most cases, if not all.
Group lookups are different.The number of members in the group can vary a lot.
{{_SC_GETGR_R_SIZE_MAX}} is usually very big and allocating this much upfront
may not be ideal. So I set the initial buffer to be 8KB and allowed it to grow
up to 2MB. Assuming average user name length of 15 bytes, 8KB will be large
enough to store a group with about 500 members. 2MB will be large enough for a
group with about 130K members.
What do you think about the new initial buffer size and the limit?
> Fix incorrect return code and allow more retries on EINTR
> ---------------------------------------------------------
>
> Key: HADOOP-10527
> URL: https://issues.apache.org/jira/browse/HADOOP-10527
> Project: Hadoop Common
> Issue Type: Bug
> Reporter: Kihwal Lee
> Assignee: Kihwal Lee
> Attachments: hadoop-10527.patch, hadoop-10527.patch,
> hadoop-10527.patch
>
>
> After HADOOP-10522, user/group look-up will only try up to 5 times on EINTR.
> More retries should be allowed just in case.
> Also, when a user/group lookup returns no entries, the wrapper methods are
> returning EIO, instead of ENOENT.
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