[jira] [Commented] (PARQUET-2202) Redundant String allocation on the hot path in CapacityByteArrayOutputStream.setByte

["ASF GitHub Bot (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/PARQUET-2202?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17693672#comment-17693672 ] 

ASF GitHub Bot commented on PARQUET-2202:
-----------------------------------------

jerolba opened a new pull request, #1035:
URL: https://github.com/apache/parquet-mr/pull/1035

   The [original Jira ticket ](https://issues.apache.org/jira/browse/PARQUET-2202) references to a concrete bad usage of the `Preconditions.checkArgument` method, where a String is calculated before validating the check, creating an overhead when in theory 100% of the cases the composed String will not be used.
   
   The proposed solution inlines the call to `Preconditions.checkArgument`, but the correct approach is to call the `checkArgument` method with a String to format if the argument check is not valid.
   
   A similar issue ocurrs in the [constructor](https://github.com/apache/parquet-mr/blob/62b774cd0f0c60cfbe540bbfa60bee15929af5d4/parquet-common/src/main/java/org/apache/parquet/bytes/CapacityByteArrayOutputStream.java#L153) of the `CapacityByteArrayOutputStream` class, where the error message is always created using the `String.format`, instead of passing the template String and its params to the `checkArgument` method. This performance issue is also visible in a profiling.
   
   The MR fixes both cases, and reviews the usage of `Preconditions` class, to ensure that error messages are not calculated before checking the boolean expression.
   
   I've also reviewed `Preconditions` methods to improve the performance. When you call to a method with a varargs argument, Java internally allocates an array containing all values. To avoid this allocation when the number of params is very low, is recomended to overload the method with versions of the method with different number of arguments. This approach is heavily used in logging frameworks, or in [Guava Preconditions implementation](https://github.com/google/guava/blob/4312d949967f3fb245636f66437a00dd8c346d38/guava/src/com/google/common/base/Preconditions.java#L118)
   Because nearly 100% of cases are going to check the condition as valid, the Array associated with varargs call to `Preconditions.strings` method will never be created.
   
   Because all changes are related with `Preconditions.checkargument`, I've created a single PR. I can split it in multiple PRs if needed. Each commit of the PR makes a type of change, but I can squash into a single commit if needed.
   
   Make sure you have checked _all_ steps below.
   
   ### Jira
   
   - [x] My PR addresses the following [Parquet Jira](https://issues.apache.org/jira/browse/PARQUET/) issues and references them in the PR title. For example, "PARQUET-2202: My Parquet PR"
     - https://issues.apache.org/jira/browse/PARQUET-2202
     - In case you are adding a dependency, check if the license complies with the [ASF 3rd Party License Policy](https://www.apache.org/legal/resolved.html#category-x).
   
   ### Tests
   
   - [x] My PR adds test cases to the following unit tests:
     1. https://github.com/jerolba/parquet-mr/blob/review_usage_of_preconditions_checkargument/parquet-common/src/test/java/org/apache/parquet/TestPreconditions.java
   
   ### Commits
   
   - [x] My commits all reference Jira issues in their subject lines. In addition, my commits follow the guidelines from "[How to write a good git commit message](http://chris.beams.io/posts/git-commit/)":
     1. Subject is separated from body by a blank line
     1. Subject is limited to 50 characters (not including Jira issue reference)
     1. Subject does not end with a period
     1. Subject uses the imperative mood ("add", not "adding")
     1. Body wraps at 72 characters
     1. Body explains "what" and "why", not "how"
   
   ### Documentation
   
   - [x] In case of new functionality, my PR adds documentation that describes how to use it.
     - All the public functions and the classes in the PR contain Javadoc that explain what it does
   




> Redundant String allocation on the hot path in CapacityByteArrayOutputStream.setByte
> ------------------------------------------------------------------------------------
>
>                 Key: PARQUET-2202
>                 URL: https://issues.apache.org/jira/browse/PARQUET-2202
>             Project: Parquet
>          Issue Type: Bug
>          Components: parquet-mr
>    Affects Versions: 1.12.3
>            Reporter: Andrei Pangin
>            Priority: Major
>              Labels: performance
>         Attachments: profile-alloc.png, profile-cpu.png
>
>
> Profiling of a Spark application revealed a performance issue in production:
> {{CapacityByteArrayOutputStream.setByte}} consumed 2.2% of total CPU time and made up 4.6% of total allocations. However, in normal case, this method should allocate nothing at all.
> Here is an excerpt from async-profiler report.
> CPU profile:
> !profile-cpu.png|width=560!
> Allocation profile:
> !profile-alloc.png|width=560!
> The reason is a {{checkArgument()}} call with an unconditionally constructed dynamic String:
> [https://github.com/apache/parquet-mr/blob/62b774cd0f0c60cfbe540bbfa60bee15929af5d4/parquet-common/src/main/java/org/apache/parquet/bytes/CapacityByteArrayOutputStream.java#L303]
> The suggested fix is to move String construction under the condition:
> {code:java}
> if (index >= bytesUsed) {
>   throw new IllegalArgumentException("Index: " + index +
>       " is >= the current size of: " + bytesUsed);
> }{code}



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