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…mentManagedBuffer

This patch eliminates duplicate strings that come from the 'path' field of
java.io.File objects created by FileSegmentManagedBuffer. That is, we want
to avoid the situation when multiple File instances for the same pathname
"foo/bar" are created, each with a separate copy of the "foo/bar" String
instance. In some scenarios such duplicate strings may waste a lot of memory
(~ 10% of the heap). To avoid that, we intern the pathname with
String.intern(), and before that we make sure that it's in a normalized
form (contains no "//", "///" etc.) Otherwise, the code in java.io.File
would normalize it later, creating a new "foo/bar" String copy.
Unfortunately, the normalization code that java.io.File uses internally
is in the package-private class java.io.FileSystem, so we cannot call it
here directly.

What changes were proposed in this pull request?

Added code to ExternalShuffleBlockResolver.getFile(), that normalizes and then interns the pathname string before passing it to the File() constructor.

How was this patch tested?

Added unit test

Author: Misha Dmitriev [email protected]

Closes apache#21456 from countmdm/misha/spark-24356.

What changes were proposed in this pull request?

(Please fill in changes proposed in this fix)

How was this patch tested?

(Please explain how this patch was tested. E.g. unit tests, integration tests, manual tests)
(If this patch involves UI changes, please attach a screenshot; otherwise, remove this)

Please review http://spark.apache.org/contributing.html before opening a pull request.

…mentManagedBuffer

This patch eliminates duplicate strings that come from the 'path' field of
java.io.File objects created by FileSegmentManagedBuffer. That is, we want
to avoid the situation when multiple File instances for the same pathname
"foo/bar" are created, each with a separate copy of the "foo/bar" String
instance. In some scenarios such duplicate strings may waste a lot of memory
(~ 10% of the heap). To avoid that, we intern the pathname with
String.intern(), and before that we make sure that it's in a normalized
form (contains no "//", "///" etc.) Otherwise, the code in java.io.File
would normalize it later, creating a new "foo/bar" String copy.
Unfortunately, the normalization code that java.io.File uses internally
is in the package-private class java.io.FileSystem, so we cannot call it
here directly.

## What changes were proposed in this pull request?

Added code to ExternalShuffleBlockResolver.getFile(), that normalizes and then interns the pathname string before passing it to the File() constructor.

## How was this patch tested?

Added unit test

Author: Misha Dmitriev <[email protected]>

Closes #21456 from countmdm/misha/spark-24356.
@GulajavaMinistudio GulajavaMinistudio merged commit 7b120fe into GulajavaMinistudio:master Jun 3, 2018
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2 participants