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https://issues.apache.org/jira/browse/HDFS-420?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13040860#comment-13040860
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Brian Bockelman commented on HDFS-420:
--------------------------------------
Hi,
I added the ref-counting in there originally because I thought I could get a
refcounting scheme to work. I really couldn't come up with a way to safely
disconnect the filesystem. OTOH, there really seems to be no reason to
disconnect the filesystem: we've had mounts lasting for a month.
I'm hoping future versions of libhdfs will help out here, so I'd like to keep
things factored out into doConnect and doDisconnect. That way we can revisit
ref-counting in the future if we'd like.
When I get back from vacation, I'll put Eli's final patch through the paces
locally.
Brian
> Fuse-dfs should cache fs handles
> --------------------------------
>
> Key: HDFS-420
> URL: https://issues.apache.org/jira/browse/HDFS-420
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: contrib/fuse-dfs
> Affects Versions: 0.20.2
> Environment: Fedora core 10, x86_64, 2.6.27.7-134.fc10.x86_64 #1 SMP
> (AMD 64), gcc 4.3.2, java 1.6.0 (IcedTea6 1.4 (fedora-7.b12.fc10-x86_64)
> Runtime Environment (build 1.6.0_0-b12) OpenJDK 64-Bit Server VM (build
> 10.0-b19, mixed mode)
> Reporter: Dima Brodsky
> Assignee: Brian Bockelman
> Fix For: 0.23.0
>
> Attachments: fuse_dfs_020_memleaks.patch,
> fuse_dfs_020_memleaks_v3.patch, fuse_dfs_020_memleaks_v8.patch,
> hdfs-420-1.patch, hdfs-420-2.patch
>
>
> Fuse-dfs should cache fs handles on a per-user basis. This significantly
> increases performance, and has the side effect of fixing the current code
> which leaks fs handles.
> The original bug description follows:
> I run the following test:
> 1. Run hadoop DFS in single node mode
> 2. start up fuse_dfs
> 3. copy my source tree, about 250 megs, into the DFS
> cp -av * /mnt/hdfs/
> in /var/log/messages I keep seeing:
> Dec 22 09:02:08 bodum fuse_dfs: ERROR: hdfs trying to utime
> /bar/backend-trunk2/src/machinery/hadoop/output/2008/11/19 to
> 1229385138/1229963739
> and then eventually
> Dec 22 09:03:49 bodum fuse_dfs: ERROR: could not connect to dfs
> fuse_dfs.c:1333
> Dec 22 09:03:49 bodum fuse_dfs: ERROR: could not connect to dfs
> fuse_dfs.c:1333
> Dec 22 09:03:49 bodum fuse_dfs: ERROR: could not connect to dfs
> fuse_dfs.c:1037
> Dec 22 09:03:49 bodum fuse_dfs: ERROR: could not connect to dfs
> fuse_dfs.c:1333
> Dec 22 09:03:49 bodum fuse_dfs: ERROR: could not connect to dfs
> fuse_dfs.c:1037
> Dec 22 09:03:49 bodum fuse_dfs: ERROR: could not connect to dfs
> fuse_dfs.c:1333
> Dec 22 09:03:49 bodum fuse_dfs: ERROR: could not connect to dfs
> fuse_dfs.c:1209
> Dec 22 09:03:49 bodum fuse_dfs: ERROR: could not connect to dfs
> fuse_dfs.c:1037
> Dec 22 09:03:49 bodum fuse_dfs: ERROR: could not connect to dfs
> fuse_dfs.c:1037
> Dec 22 09:03:49 bodum fuse_dfs: ERROR: could not connect to dfs
> fuse_dfs.c:1037
> Dec 22 09:03:49 bodum fuse_dfs: ERROR: could not connect to dfs
> fuse_dfs.c:1037
> Dec 22 09:03:49 bodum fuse_dfs: ERROR: could not connect to dfs
> fuse_dfs.c:1037
> Dec 22 09:03:49 bodum fuse_dfs: ERROR: could not connect to dfs
> fuse_dfs.c:1037
> Dec 22 09:03:49 bodum fuse_dfs: ERROR: could not connect to dfs
> fuse_dfs.c:1037
> Dec 22 09:03:49 bodum fuse_dfs: ERROR: could not connect to dfs
> fuse_dfs.c:1037
> Dec 22 09:03:49 bodum fuse_dfs: ERROR: could not connect to dfs
> fuse_dfs.c:1037
> Dec 22 09:03:49 bodum fuse_dfs: ERROR: could not connect to dfs
> fuse_dfs.c:1209
> Dec 22 09:03:49 bodum fuse_dfs: ERROR: could not connect to dfs
> fuse_dfs.c:1037
> Dec 22 09:03:49 bodum fuse_dfs: ERROR: could not connect to dfs
> fuse_dfs.c:1037
> Dec 22 09:03:49 bodum fuse_dfs: ERROR: could not connect to dfs
> fuse_dfs.c:1037
> Dec 22 09:03:49 bodum fuse_dfs: ERROR: could not connect to dfs
> fuse_dfs.c:1333
> Dec 22 09:03:49 bodum fuse_dfs: ERROR: could not connect to dfs
> fuse_dfs.c:1209
> Dec 22 09:03:49 bodum fuse_dfs: ERROR: could not connect to dfs
> fuse_dfs.c:1037
> and the file system hangs. hadoop is still running and I don't see any
> errors in it's logs. I have to unmount the dfs and restart fuse_dfs and then
> everything is fine again. At some point I see the following messages in the
> /var/log/messages:
> ERROR: dfs problem - could not close file_handle(139677114350528) for
> /bar/backend-trunk2/src/machinery/hadoop/input/2008/12/14/actionrecordlog-8339-93825052368848-1229278807.log
> fuse_dfs.c:1464
> Dec 22 09:04:49 bodum fuse_dfs: ERROR: dfs problem - could not close
> file_handle(139676770220176) for
> /bar/backend-trunk2/src/machinery/hadoop/input/2008/12/14/actionrecordlog-8140-93825025883216-1229278759.log
> fuse_dfs.c:1464
> Dec 22 09:05:13 bodum fuse_dfs: ERROR: dfs problem - could not close
> file_handle(139677114812832) for
> /bar/backend-trunk2/src/machinery/hadoop/input/2008/12/14/actionrecordlog-8138-93825070138960-1229251587.log
> fuse_dfs.c:1464
> Is this a known issue? Am I just flooding the system too much. All of this
> is being performed on a single, dual core, machine.
> Thanks!
> ttyl
> Dima
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