[jira] [Comment Edited] (IGNITE-2265) Replace Atomic* variables with field updaters.

["Vladimir Ozerov (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/IGNITE-2265?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15071248#comment-15071248 ] 

Vladimir Ozerov edited comment on IGNITE-2265 at 12/24/15 9:11 PM:
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Andrey,

You are asking tough questions :-) It is hard to reason whether particular microoptimziation will give any observable benefit or not. 

Basically, I am trying to find places which could speedup the product. Clearly, there are lot of them. So for now I am looking for suspicious code pieces which are both a) easy to improve; b) have good chances to increase overall performance.
To identify them I simply run base scenarios like GET/PUT and see profiler results in terms of hot execution paths and memory allocations. 

Atomic* variables is one of the hotspots revealed by profiler. Some atomics are located inside our cache futures which are created on virually any cache operation. And in a simple benchmark with distributed cache GET, these Atomics* are responsible for 2-3% of all heap allocations  We can easily get rid of these Atomics and decrease memory pressure. 

2-3% is not a big number when considered separately. But if more similar optimizations are applied, we could reduce memory pressure in common scenarios by about 20-25% with minimal efforts. I log such potentially promising finding as subtask to the parent ticket IGNITE-2232.


was (Author: vozerov):
Andrey,

You are asking tough questions :-) It is hard to reason whether particular microoptimziation will give any observable benefit or not. 

Basically, I am trying to find places which could speedup the product. Clearly, there are lot of them. So for now I am looking for suspicious code pieces which are both a) easy to improve; b) have good chances to increase overall performance.
To identify them I simply run base scenarios like GET/PUT and see profiler results in terms of hot execution paths and memory allocations. 

Atomic* variables is one of the hotspot which were revealed by profiler. Some atomics are located inside our cache futures which are created on virually any cache operation. And in a simple benchmark with distributed cache GET, these Atomics* are responsible for 2-3% of all heap allocations  We can easily get rid of these Atomics and decrease memory pressure. 

2-3% is not a big number when considered separately. But if more similar optimizations are applied, we could reduce memory pressure in common scenarios by about 20-25% with minimal efforts. I log such potentially promising finding as subtask to the parent ticket IGNITE-2232.

> Replace Atomic* variables with field updaters.
> ----------------------------------------------
>
>                 Key: IGNITE-2265
>                 URL: https://issues.apache.org/jira/browse/IGNITE-2265
>             Project: Ignite
>          Issue Type: Sub-task
>          Components: general
>    Affects Versions: ignite-1.4
>            Reporter: Vladimir Ozerov
>            Assignee: Vladimir Ozerov
>             Fix For: 1.6
>
>
> Field updaters must be used instaed of the following classes:
> 1) AtomicInteger
> 2) AtomicLong
> 3) AtomicReference
> 4) If AtomicBoolean is met in some hot spaces, it must be replaced with (int + updater) pair. 



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