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From "Aleksey Plekhanov (JIRA)" <j...@apache.org>
Subject [jira] [Assigned] (IGNITE-11911) GridToStringBuilder allocates redundant memory
Date Tue, 11 Jun 2019 12:59:00 GMT

     [ https://issues.apache.org/jira/browse/IGNITE-11911?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Aleksey Plekhanov reassigned IGNITE-11911:
------------------------------------------

    Assignee: Aleksey Plekhanov

> GridToStringBuilder allocates redundant memory
> ----------------------------------------------
>
>                 Key: IGNITE-11911
>                 URL: https://issues.apache.org/jira/browse/IGNITE-11911
>             Project: Ignite
>          Issue Type: Bug
>    Affects Versions: 2.7
>            Reporter: Aleksey Plekhanov
>            Assignee: Aleksey Plekhanov
>            Priority: Major
>
> A lot of classes in Ignite uses {{GridToStringBuilder}} to implement their {{toString()}}
method. {{GridToStringBuilder}} uses thread local buffer to generate string representation.
This buffer extended on demand but never shrank. On the final step {{GridToStringBuilder}}
uses java {{StringBuilder}} class to produce output string and uses own buffer size as
{{StringBuilder}} initial capacity. This leads to unnecessary memory allocation since we
only need to allocate memory for meaningful data, but not for all buffer.
>  Reproducer:
>  
> {code:java}
> public void testSB() {
>     GridToStringBuilder.toString(C1.class, new C1(1_000_000));
>     GridToStringBuilder.toString(C1.class, new C1(100));
> }
> public class C1 {
>     private String f;
>     C1(int len) {
>         f = new String(new char[len]);
>     }
> }
> {code}
> Here on the second line about 1 million chars StringBuilder will be allocated, but only
about 100 chars needed.
>  
> Problem code (SBLimitedLength.java:293):
>  
> {code:java}
> StringBuilder res = new StringBuilder(impl().capacity() + tailLen + 100);
> {code}
> Here {{length()}} method can be used instead of {{capacity()}}
>  



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