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https://issues.apache.org/jira/browse/LENS-279?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Himanshu Gahlaut updated LENS-279:
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Description: Currently writeExternal method of various lens classes writes
to an ObjectOutputStream for persisting state of objects. These writeExternal
method calls are triggered from a code block in LensServices class which is a
synchronized code block. All write methods are coming within synchronized
blocks in all classes. write method can take long time due to slowness in
filesystem and that can block other synchronized methods in these classes,
which come under query execution flow. This locking and slowness in filesystem
can decrease the performance of query execution flow. An improved approach can
be to make a copy of the entire state to be persisted, with synchronization,
and then write to file system in a non synchronized code block. This would
result in locking a lighter portion of code (in memory copy) instead of
creating locks around relatively heavier portion of code (writes to
filesystem). (was: Currently writeExternal method of various lens classes
writes to an ObjectOutputStream for persisting state of objects. These
writeExternal method calls are triggered from a code block in LensServices
class which is a synchronized code block. All write methods are coming within
synchronized blocks in all classes. write method can take long time due to
slowness in filesystem and that can block other synchronized methods in these
classes, which come under query execution flow. This locking and slowness in
filesystem can decrease the performance of query execution flow. An improved
approach can be to make a copy of the entire state to be persisted with
synchronization and then write to file system in a non synchronized code block.
This would result in locking a lighter portion of code (in memory copy) instead
of creating locks around relatively heavier portion of code (writes to
filesystem). )
> Redesigning lens server state persistence with respect to synchronization
> -------------------------------------------------------------------------
>
> Key: LENS-279
> URL: https://issues.apache.org/jira/browse/LENS-279
> Project: Apache Lens
> Issue Type: Improvement
> Reporter: Himanshu Gahlaut
>
> Currently writeExternal method of various lens classes writes to an
> ObjectOutputStream for persisting state of objects. These writeExternal
> method calls are triggered from a code block in LensServices class which is a
> synchronized code block. All write methods are coming within synchronized
> blocks in all classes. write method can take long time due to slowness in
> filesystem and that can block other synchronized methods in these classes,
> which come under query execution flow. This locking and slowness in
> filesystem can decrease the performance of query execution flow. An improved
> approach can be to make a copy of the entire state to be persisted, with
> synchronization, and then write to file system in a non synchronized code
> block. This would result in locking a lighter portion of code (in memory
> copy) instead of creating locks around relatively heavier portion of code
> (writes to filesystem).
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