Thanks.

On Nov 26, 2007, at 1:34 PM, Michael McCandless wrote:


It's the "write" method in o.a.l.index.SegmentInfos

It's called from IndexWriter/DirectoryIndexReader.

Mike

"robert engels" <[EMAIL PROTECTED]> wrote:
Can you point me to the code that does the actual writing of the
SEGMENTS.XXX file?

On Nov 26, 2007, at 1:16 PM, Michael McCandless wrote:


This is correct.

This just means the DeletionPolicy cannot delete a commit point until
all files referenced by a future (the next) commit point are done
being sync'd (DeletionPolicy needs to query the Directory to find out
which files are on stable storage).

However before we even go there, I'm going to run perf tests of
background sync'ing to see if it can reduce the cost of syncing.

Mike

"robert engels" <[EMAIL PROTECTED]> wrote:
I am not sure all of this effort is going to work anyway...

I think you need to sync all of the segment files, THEN write the
segments.XXXX file and sync it.

It does you no good if there is a valid segments.XXX file, but some
of the dependent files may not have written successfully to disk.

By the proper ordering of the operations

write files
sync files
write SEGMENTS FILE with chceksum, and sync

is the only way to be certain the index is not internally corrupt.

I have not looked at closely, so it may already be doing this (but I
don't think so).  Code is getting a bit hard to follow for me.

On Nov 26, 2007, at 12:14 PM, Doug Cutting (JIRA) wrote:


    [ https://issues.apache.org/jira/browse/LUCENE-1044?
page=com.atlassian.jira.plugin.system.issuetabpanels:comment-
tabpanel#action_12545535 ]

Doug Cutting commented on LUCENE-1044:
--------------------------------------

I found out however that delaying the syncs (but intending to
sync) also
means keeping the file handles open [...]

Not necessarily.  You could just queue the file names for sync,
close them, and then have the background thread open, sync and
close them.  The close could trigger the OS to sync things faster
in the background.  Then the open/sync/close could mostly be a no-
op.  Might be worth a try.

Behavior on hard power shutdown
-------------------------------

                Key: LUCENE-1044
                URL: https://issues.apache.org/jira/browse/
LUCENE-1044
            Project: Lucene - Java
         Issue Type: Bug
         Components: Index
        Environment: Windows Server 2003, Standard Edition, Sun
Hotspot Java 1.5
           Reporter: venkat rangan
           Assignee: Michael McCandless
            Fix For: 2.3

        Attachments: FSyncPerfTest.java, LUCENE-1044.patch,
LUCENE-1044.take2.patch, LUCENE-1044.take3.patch


When indexing a large number of documents, upon a hard power
failure  (e.g. pull the power cord), the index seems to get
corrupted. We start a Java application as an Windows Service, and
feed it documents. In some cases (after an index size of 1.7GB,
with 30-40 index segment .cfs files) , the following is observed.
The 'segments' file contains only zeros. Its size is 265 bytes -
all bytes are zeros.
The 'deleted' file also contains only zeros. Its size is 85 bytes
- all bytes are zeros.
Before corruption, the segments file and deleted file appear to be
correct. After this corruption, the index is corrupted and lost.
This is a problem observed in Lucene 1.4.3. We are not able to
upgrade our customer deployments to 1.9 or later version, but
would be happy to back-port a patch, if the patch is small enough
and if this problem is already solved.

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