FAQ
tasktracker hang in reduce. Deadlock between main and comm thread
-----------------------------------------------------------------

Key: HADOOP-1970
URL: https://issues.apache.org/jira/browse/HADOOP-1970
Project: Hadoop
Issue Type: Bug
Components: mapred
Affects Versions: 0.14.1
Reporter: Koji Noguchi
Priority: Blocker
Fix For: 0.14.2


Saw one reduce task stuck on copy.
jstack on the reduce task(task_200709272248_0001_r_000150_0) process showed

Found one Java-level deadlock:
=============================
"Comm thread for task_200709272248_0001_r_000150_0":
waiting to lock monitor 0x08144020 (object 0xd4e30aa8, a org.apache.hadoop.util.Progress),
which is held by "main"
"main":
waiting to lock monitor 0x08144084 (object 0xd4e30958, a org.apache.hadoop.util.Progress),
which is held by "Comm thread for task_200709272248_0001_r_000150_0"

Java stack information for the threads listed above:
===================================================
"Comm thread for task_200709272248_0001_r_000150_0":
at org.apache.hadoop.util.Progress.toString(Progress.java:113)
- waiting to lock <0xd4e30aa8> (a org.apache.hadoop.util.Progress)
at org.apache.hadoop.util.Progress.toString(Progress.java:116)
- locked <0xd4e30958> (a org.apache.hadoop.util.Progress)
at org.apache.hadoop.util.Progress.toString(Progress.java:108)
at org.apache.hadoop.mapred.Task$1.run(Task.java:268)
at java.lang.Thread.run(Thread.java:619)
"main":
at org.apache.hadoop.util.Progress.startNextPhase(Progress.java:58)
- waiting to lock <0xd4e30958> (a org.apache.hadoop.util.Progress)
at org.apache.hadoop.util.Progress.complete(Progress.java:70)
- locked <0xd4e30aa8> (a org.apache.hadoop.util.Progress)
at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:253)
at org.apache.hadoop.mapred.TaskTracker$Child.main(TaskTracker.java:1777)


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  • Koji Noguchi (JIRA) at Sep 29, 2007 at 7:10 am
    [ https://issues.apache.org/jira/browse/HADOOP-1970?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

    Koji Noguchi updated HADOOP-1970:
    ---------------------------------

    Description:
    Saw one reduce task stuck on copy.
    jstack on the reduce task(task_200709272248_0001_r_000150_0) process showed

    {noformat}
    Found one Java-level deadlock:
    =============================
    "Comm thread for task_200709272248_0001_r_000150_0":
    waiting to lock monitor 0x08144020 (object 0xd4e30aa8, a org.apache.hadoop.util.Progress),
    which is held by "main"
    "main":
    waiting to lock monitor 0x08144084 (object 0xd4e30958, a org.apache.hadoop.util.Progress),
    which is held by "Comm thread for task_200709272248_0001_r_000150_0"

    Java stack information for the threads listed above:
    ===================================================
    "Comm thread for task_200709272248_0001_r_000150_0":
    at org.apache.hadoop.util.Progress.toString(Progress.java:113)
    - waiting to lock <0xd4e30aa8> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.toString(Progress.java:116)
    - locked <0xd4e30958> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.toString(Progress.java:108)
    at org.apache.hadoop.mapred.Task$1.run(Task.java:268)
    at java.lang.Thread.run(Thread.java:619)
    "main":
    at org.apache.hadoop.util.Progress.startNextPhase(Progress.java:58)
    - waiting to lock <0xd4e30958> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.complete(Progress.java:70)
    - locked <0xd4e30aa8> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:253)
    at org.apache.hadoop.mapred.TaskTracker$Child.main(TaskTracker.java:1777)
    {noformat}

    was:
    Saw one reduce task stuck on copy.
    jstack on the reduce task(task_200709272248_0001_r_000150_0) process showed

    Found one Java-level deadlock:
    =============================
    "Comm thread for task_200709272248_0001_r_000150_0":
    waiting to lock monitor 0x08144020 (object 0xd4e30aa8, a org.apache.hadoop.util.Progress),
    which is held by "main"
    "main":
    waiting to lock monitor 0x08144084 (object 0xd4e30958, a org.apache.hadoop.util.Progress),
    which is held by "Comm thread for task_200709272248_0001_r_000150_0"

    Java stack information for the threads listed above:
    ===================================================
    "Comm thread for task_200709272248_0001_r_000150_0":
    at org.apache.hadoop.util.Progress.toString(Progress.java:113)
    - waiting to lock <0xd4e30aa8> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.toString(Progress.java:116)
    - locked <0xd4e30958> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.toString(Progress.java:108)
    at org.apache.hadoop.mapred.Task$1.run(Task.java:268)
    at java.lang.Thread.run(Thread.java:619)
    "main":
    at org.apache.hadoop.util.Progress.startNextPhase(Progress.java:58)
    - waiting to lock <0xd4e30958> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.complete(Progress.java:70)
    - locked <0xd4e30aa8> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:253)
    at org.apache.hadoop.mapred.TaskTracker$Child.main(TaskTracker.java:1777)


    tasktracker hang in reduce. Deadlock between main and comm thread
    -----------------------------------------------------------------

    Key: HADOOP-1970
    URL: https://issues.apache.org/jira/browse/HADOOP-1970
    Project: Hadoop
    Issue Type: Bug
    Components: mapred
    Affects Versions: 0.14.1
    Reporter: Koji Noguchi
    Priority: Blocker
    Fix For: 0.14.2


    Saw one reduce task stuck on copy.
    jstack on the reduce task(task_200709272248_0001_r_000150_0) process showed
    {noformat}
    Found one Java-level deadlock:
    =============================
    "Comm thread for task_200709272248_0001_r_000150_0":
    waiting to lock monitor 0x08144020 (object 0xd4e30aa8, a org.apache.hadoop.util.Progress),
    which is held by "main"
    "main":
    waiting to lock monitor 0x08144084 (object 0xd4e30958, a org.apache.hadoop.util.Progress),
    which is held by "Comm thread for task_200709272248_0001_r_000150_0"
    Java stack information for the threads listed above:
    ===================================================
    "Comm thread for task_200709272248_0001_r_000150_0":
    at org.apache.hadoop.util.Progress.toString(Progress.java:113)
    - waiting to lock <0xd4e30aa8> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.toString(Progress.java:116)
    - locked <0xd4e30958> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.toString(Progress.java:108)
    at org.apache.hadoop.mapred.Task$1.run(Task.java:268)
    at java.lang.Thread.run(Thread.java:619)
    "main":
    at org.apache.hadoop.util.Progress.startNextPhase(Progress.java:58)
    - waiting to lock <0xd4e30958> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.complete(Progress.java:70)
    - locked <0xd4e30aa8> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:253)
    at org.apache.hadoop.mapred.TaskTracker$Child.main(TaskTracker.java:1777)
    {noformat}
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  • Devaraj Das (JIRA) at Oct 1, 2007 at 4:29 am
    [ https://issues.apache.org/jira/browse/HADOOP-1970?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

    Devaraj Das reassigned HADOOP-1970:
    -----------------------------------

    Assignee: Vivek Ratan
    tasktracker hang in reduce. Deadlock between main and comm thread
    -----------------------------------------------------------------

    Key: HADOOP-1970
    URL: https://issues.apache.org/jira/browse/HADOOP-1970
    Project: Hadoop
    Issue Type: Bug
    Components: mapred
    Affects Versions: 0.14.1
    Reporter: Koji Noguchi
    Assignee: Vivek Ratan
    Priority: Blocker
    Fix For: 0.14.2


    Saw one reduce task stuck on copy.
    jstack on the reduce task(task_200709272248_0001_r_000150_0) process showed
    {noformat}
    Found one Java-level deadlock:
    =============================
    "Comm thread for task_200709272248_0001_r_000150_0":
    waiting to lock monitor 0x08144020 (object 0xd4e30aa8, a org.apache.hadoop.util.Progress),
    which is held by "main"
    "main":
    waiting to lock monitor 0x08144084 (object 0xd4e30958, a org.apache.hadoop.util.Progress),
    which is held by "Comm thread for task_200709272248_0001_r_000150_0"
    Java stack information for the threads listed above:
    ===================================================
    "Comm thread for task_200709272248_0001_r_000150_0":
    at org.apache.hadoop.util.Progress.toString(Progress.java:113)
    - waiting to lock <0xd4e30aa8> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.toString(Progress.java:116)
    - locked <0xd4e30958> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.toString(Progress.java:108)
    at org.apache.hadoop.mapred.Task$1.run(Task.java:268)
    at java.lang.Thread.run(Thread.java:619)
    "main":
    at org.apache.hadoop.util.Progress.startNextPhase(Progress.java:58)
    - waiting to lock <0xd4e30958> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.complete(Progress.java:70)
    - locked <0xd4e30aa8> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:253)
    at org.apache.hadoop.mapred.TaskTracker$Child.main(TaskTracker.java:1777)
    {noformat}
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  • Arun C Murthy (JIRA) at Oct 1, 2007 at 5:35 am
    [ https://issues.apache.org/jira/browse/HADOOP-1970?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12531411 ]

    Arun C Murthy commented on HADOOP-1970:
    ---------------------------------------

    Ok, this is indeed a deadlock... the issue is that there is a differing order of locks of the parent and child Progress objects in Progress.java.

    As shown in the stack trace {{Progress.complete}} locks the child first and then the parent, where as {{Progress.toString(StringBuffer)}} locks the parent first and then the child... straight-forward fix is to ensure that parent is always locked first e.g. in {{Progress.complete}}.
    tasktracker hang in reduce. Deadlock between main and comm thread
    -----------------------------------------------------------------

    Key: HADOOP-1970
    URL: https://issues.apache.org/jira/browse/HADOOP-1970
    Project: Hadoop
    Issue Type: Bug
    Components: mapred
    Affects Versions: 0.14.1
    Reporter: Koji Noguchi
    Assignee: Vivek Ratan
    Priority: Blocker
    Fix For: 0.14.2


    Saw one reduce task stuck on copy.
    jstack on the reduce task(task_200709272248_0001_r_000150_0) process showed
    {noformat}
    Found one Java-level deadlock:
    =============================
    "Comm thread for task_200709272248_0001_r_000150_0":
    waiting to lock monitor 0x08144020 (object 0xd4e30aa8, a org.apache.hadoop.util.Progress),
    which is held by "main"
    "main":
    waiting to lock monitor 0x08144084 (object 0xd4e30958, a org.apache.hadoop.util.Progress),
    which is held by "Comm thread for task_200709272248_0001_r_000150_0"
    Java stack information for the threads listed above:
    ===================================================
    "Comm thread for task_200709272248_0001_r_000150_0":
    at org.apache.hadoop.util.Progress.toString(Progress.java:113)
    - waiting to lock <0xd4e30aa8> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.toString(Progress.java:116)
    - locked <0xd4e30958> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.toString(Progress.java:108)
    at org.apache.hadoop.mapred.Task$1.run(Task.java:268)
    at java.lang.Thread.run(Thread.java:619)
    "main":
    at org.apache.hadoop.util.Progress.startNextPhase(Progress.java:58)
    - waiting to lock <0xd4e30958> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.complete(Progress.java:70)
    - locked <0xd4e30aa8> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:253)
    at org.apache.hadoop.mapred.TaskTracker$Child.main(TaskTracker.java:1777)
    {noformat}
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  • Vivek Ratan (JIRA) at Oct 1, 2007 at 8:32 am
    [ https://issues.apache.org/jira/browse/HADOOP-1970?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

    Vivek Ratan updated HADOOP-1970:
    --------------------------------

    Attachment: 1970_patch01

    Well, it's a little bigger than that. What's happening is that there are 2-3 methods that traverse the tree-like structure of Progress methods, and at least two of them traverse (and obtain locks) in different directions, hence the deadlock. (One of) the right solution is to obtain locks in one direction only - so we lock when going downwards from the root node. This happens in get(), getInternal(), and toString(). If you need to traverse upwards towards the root (in complete()), you either release your lock before getting your parent's (which is what I've chosen to do, since we don't need transactional semantics), or you get locks in the same direction as other traversal methods.

    Another somewhat related issue is that Progress::get(), which is called quite often, always traverses upwards to find the root of a structure. Since a node's root never changes, it should be cached at each node. This certainly improves performance for get(), but it also offers a synch mechanism should we ever need to write code that needs to lock multiple nodes and traverse upwards towards the root. In such a case, the methods can lock the root object to get sole access control to the entire structure. We don't need this for now, but it's a good mechanism to have for the future.

    I have attached a patch (1970_patch01) with these changes, along with lots of comments for reference.
    tasktracker hang in reduce. Deadlock between main and comm thread
    -----------------------------------------------------------------

    Key: HADOOP-1970
    URL: https://issues.apache.org/jira/browse/HADOOP-1970
    Project: Hadoop
    Issue Type: Bug
    Components: mapred
    Affects Versions: 0.14.1
    Reporter: Koji Noguchi
    Assignee: Vivek Ratan
    Priority: Blocker
    Fix For: 0.14.2

    Attachments: 1970_patch01


    Saw one reduce task stuck on copy.
    jstack on the reduce task(task_200709272248_0001_r_000150_0) process showed
    {noformat}
    Found one Java-level deadlock:
    =============================
    "Comm thread for task_200709272248_0001_r_000150_0":
    waiting to lock monitor 0x08144020 (object 0xd4e30aa8, a org.apache.hadoop.util.Progress),
    which is held by "main"
    "main":
    waiting to lock monitor 0x08144084 (object 0xd4e30958, a org.apache.hadoop.util.Progress),
    which is held by "Comm thread for task_200709272248_0001_r_000150_0"
    Java stack information for the threads listed above:
    ===================================================
    "Comm thread for task_200709272248_0001_r_000150_0":
    at org.apache.hadoop.util.Progress.toString(Progress.java:113)
    - waiting to lock <0xd4e30aa8> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.toString(Progress.java:116)
    - locked <0xd4e30958> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.toString(Progress.java:108)
    at org.apache.hadoop.mapred.Task$1.run(Task.java:268)
    at java.lang.Thread.run(Thread.java:619)
    "main":
    at org.apache.hadoop.util.Progress.startNextPhase(Progress.java:58)
    - waiting to lock <0xd4e30958> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.complete(Progress.java:70)
    - locked <0xd4e30aa8> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:253)
    at org.apache.hadoop.mapred.TaskTracker$Child.main(TaskTracker.java:1777)
    {noformat}
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  • Vivek Ratan (JIRA) at Oct 1, 2007 at 10:32 am
    [ https://issues.apache.org/jira/browse/HADOOP-1970?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

    Vivek Ratan updated HADOOP-1970:
    --------------------------------

    Attachment: 1970_patch02

    Since this is a fix for 0.14.2, and I shouldn't be adding any new functionality, I've only fixed the problem with the deadlock in 1970_patch02. In a separate issues (HADOOP-1974), I have detailed the larger solution, including caching the root node.
    tasktracker hang in reduce. Deadlock between main and comm thread
    -----------------------------------------------------------------

    Key: HADOOP-1970
    URL: https://issues.apache.org/jira/browse/HADOOP-1970
    Project: Hadoop
    Issue Type: Bug
    Components: mapred
    Affects Versions: 0.14.1
    Reporter: Koji Noguchi
    Assignee: Vivek Ratan
    Priority: Blocker
    Fix For: 0.14.2

    Attachments: 1970_patch01, 1970_patch02


    Saw one reduce task stuck on copy.
    jstack on the reduce task(task_200709272248_0001_r_000150_0) process showed
    {noformat}
    Found one Java-level deadlock:
    =============================
    "Comm thread for task_200709272248_0001_r_000150_0":
    waiting to lock monitor 0x08144020 (object 0xd4e30aa8, a org.apache.hadoop.util.Progress),
    which is held by "main"
    "main":
    waiting to lock monitor 0x08144084 (object 0xd4e30958, a org.apache.hadoop.util.Progress),
    which is held by "Comm thread for task_200709272248_0001_r_000150_0"
    Java stack information for the threads listed above:
    ===================================================
    "Comm thread for task_200709272248_0001_r_000150_0":
    at org.apache.hadoop.util.Progress.toString(Progress.java:113)
    - waiting to lock <0xd4e30aa8> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.toString(Progress.java:116)
    - locked <0xd4e30958> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.toString(Progress.java:108)
    at org.apache.hadoop.mapred.Task$1.run(Task.java:268)
    at java.lang.Thread.run(Thread.java:619)
    "main":
    at org.apache.hadoop.util.Progress.startNextPhase(Progress.java:58)
    - waiting to lock <0xd4e30958> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.complete(Progress.java:70)
    - locked <0xd4e30aa8> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:253)
    at org.apache.hadoop.mapred.TaskTracker$Child.main(TaskTracker.java:1777)
    {noformat}
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  • Owen O'Malley (JIRA) at Oct 2, 2007 at 11:04 pm
    [ https://issues.apache.org/jira/browse/HADOOP-1970?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

    Owen O'Malley resolved HADOOP-1970.
    -----------------------------------

    Resolution: Fixed

    I just committed this. Thanks, Vivek!

    (In the future, please generate your patches without the prefix using svn diff from the HADOOP_HOME.
    tasktracker hang in reduce. Deadlock between main and comm thread
    -----------------------------------------------------------------

    Key: HADOOP-1970
    URL: https://issues.apache.org/jira/browse/HADOOP-1970
    Project: Hadoop
    Issue Type: Bug
    Components: mapred
    Affects Versions: 0.14.1
    Reporter: Koji Noguchi
    Assignee: Vivek Ratan
    Priority: Blocker
    Fix For: 0.14.2

    Attachments: 1970_patch01, 1970_patch02


    Saw one reduce task stuck on copy.
    jstack on the reduce task(task_200709272248_0001_r_000150_0) process showed
    {noformat}
    Found one Java-level deadlock:
    =============================
    "Comm thread for task_200709272248_0001_r_000150_0":
    waiting to lock monitor 0x08144020 (object 0xd4e30aa8, a org.apache.hadoop.util.Progress),
    which is held by "main"
    "main":
    waiting to lock monitor 0x08144084 (object 0xd4e30958, a org.apache.hadoop.util.Progress),
    which is held by "Comm thread for task_200709272248_0001_r_000150_0"
    Java stack information for the threads listed above:
    ===================================================
    "Comm thread for task_200709272248_0001_r_000150_0":
    at org.apache.hadoop.util.Progress.toString(Progress.java:113)
    - waiting to lock <0xd4e30aa8> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.toString(Progress.java:116)
    - locked <0xd4e30958> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.toString(Progress.java:108)
    at org.apache.hadoop.mapred.Task$1.run(Task.java:268)
    at java.lang.Thread.run(Thread.java:619)
    "main":
    at org.apache.hadoop.util.Progress.startNextPhase(Progress.java:58)
    - waiting to lock <0xd4e30958> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.complete(Progress.java:70)
    - locked <0xd4e30aa8> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:253)
    at org.apache.hadoop.mapred.TaskTracker$Child.main(TaskTracker.java:1777)
    {noformat}
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  • Hudson (JIRA) at Oct 3, 2007 at 12:27 pm
    [ https://issues.apache.org/jira/browse/HADOOP-1970?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12532075 ]

    Hudson commented on HADOOP-1970:
    --------------------------------

    Integrated in Hadoop-Nightly #259 (See [http://lucene.zones.apache.org:8080/hudson/job/Hadoop-Nightly/259/])
    tasktracker hang in reduce. Deadlock between main and comm thread
    -----------------------------------------------------------------

    Key: HADOOP-1970
    URL: https://issues.apache.org/jira/browse/HADOOP-1970
    Project: Hadoop
    Issue Type: Bug
    Components: mapred
    Affects Versions: 0.14.1
    Reporter: Koji Noguchi
    Assignee: Vivek Ratan
    Priority: Blocker
    Fix For: 0.14.2

    Attachments: 1970_patch01, 1970_patch02


    Saw one reduce task stuck on copy.
    jstack on the reduce task(task_200709272248_0001_r_000150_0) process showed
    {noformat}
    Found one Java-level deadlock:
    =============================
    "Comm thread for task_200709272248_0001_r_000150_0":
    waiting to lock monitor 0x08144020 (object 0xd4e30aa8, a org.apache.hadoop.util.Progress),
    which is held by "main"
    "main":
    waiting to lock monitor 0x08144084 (object 0xd4e30958, a org.apache.hadoop.util.Progress),
    which is held by "Comm thread for task_200709272248_0001_r_000150_0"
    Java stack information for the threads listed above:
    ===================================================
    "Comm thread for task_200709272248_0001_r_000150_0":
    at org.apache.hadoop.util.Progress.toString(Progress.java:113)
    - waiting to lock <0xd4e30aa8> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.toString(Progress.java:116)
    - locked <0xd4e30958> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.toString(Progress.java:108)
    at org.apache.hadoop.mapred.Task$1.run(Task.java:268)
    at java.lang.Thread.run(Thread.java:619)
    "main":
    at org.apache.hadoop.util.Progress.startNextPhase(Progress.java:58)
    - waiting to lock <0xd4e30958> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.util.Progress.complete(Progress.java:70)
    - locked <0xd4e30aa8> (a org.apache.hadoop.util.Progress)
    at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:253)
    at org.apache.hadoop.mapred.TaskTracker$Child.main(TaskTracker.java:1777)
    {noformat}
    --
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postedSep 29, '07 at 7:08a
activeOct 3, '07 at 12:27p
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