Re: Storage Manager crash at mdwrite() - Mailing list pgsql-hackers
| From | Tareq Aljabban |
|---|---|
| Subject | Re: Storage Manager crash at mdwrite() |
| Date | |
| Msg-id | CAGOe0aLqb18ZYWw6C77z_rcUMQyPfA0W2sWGuT5VTxZ7YDmAfw@mail.gmail.com Whole thread Raw |
| In response to | Re: Storage Manager crash at mdwrite() (Jeff Davis <pgsql@j-davis.com>) |
| Responses |
Re: Storage Manager crash at mdwrite()
|
| List | pgsql-hackers |
When configuring postgreSQL, I'm adding the libraries needed to run HDFS C API (libhdfs).
./configure --prefix=/diskless/myUser/Workspace/EclipseWS1/pgsql --enable-depend --enable-cassert --enable-debug CFLAGS="$CFLAGS -I/diskless/myUser/Workspace/HDFS_Append/hdfs/src/c++/libhdfs -I/usr/lib/jvm/default-java/include" LDFLAGS="$LDFLAGS -L/diskless/myUser/Workspace/HDFS_Append/hdfs/src/c++/libhdfs -L/diskless/myUser/Workspace/HDFS_Append/build/c++/Linux-i386-32/lib -L/usr/lib/jvm/default-java/jre/lib/i386/server -ljvm -lhdfs"
I have done lots of changes so far on how the storage manager works. In fact, I changed smgr.c so instead of calling regular md.c functions, that it would call my functions .
For simplicity, you can say that whenever mdwrite() was supposed to be called, another function is also called beside it. so now what is being called is:
mdwrite(param1, param2, buffer, ....);
hdfswrite(param1, param2, buffer, ....);
where hdfswrite() is the function where I write the buffer to HDFS.
I changed hdfswrite() so it will always write only the same (dummy) buffer down to HDFS storage. Let's say "dummyBufferFile". After writing this file 3 times to HDFS, I'm getting the message that I've shown in my first email.
The same hdfswrite() code works without any issues when I run it in a separate application.
Hope it's clear now.
On Thu, Mar 15, 2012 at 5:28 PM, Jeff Davis <pgsql@j-davis.com> wrote:
On Thu, 2012-03-15 at 13:49 -0400, Tareq Aljabban wrote:...
> I'm implementing an extention to mdwrite() at
> backend/storage/smgr/md.c
> When a block is written to the local storage using mdwrite(), I'm
> sending this block to an HDFS storage.
> So far I don't need to read back the values I'm writing to HDFS. This
> approach is working fine in the initDB phase.
> However, when I'm running postgres (bin/pg_ctl start), the first few
> write operations run successfully, and then suddenly (after writing
> exactly 3 files to HDFS), I get a 130 exit code with the following
> message showing the JVM thread dump of HDFS:
>
>
> LOG: background writer process (PID 29347) exited with exit code 130
> LOG: terminating any other active server processesWhat code, exactly, did you change in md.c, and anywhere else in
> This seems like an HDFS issue, but the same code worked properly in
> initDB(). I replaced this HDFS write code with a code that writes
> always the same block (empty one) to HDFS regardless from the value
> received by mdwrite().. Kept getting the same issue after writing 3
> files.
> I copied this exact code to a separate C application and ran it there
> and it executed without any problems (I wrote/deleted 100 files).
> That's why I'm doubting that it's something related to postgreSQL.
>
>
> Any ideas on what's going wrong?
postgres? Are you linking in new libraries/code from somewhere into the
postgres backend?
Regards,
Jeff Davis
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