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List:       openjdk-hotspot-runtime-dev
Subject:    Integrated: JDK-8303051: Stop saving 5 chunks in each ChunkPool
From:       Johan =?UTF-8?B?U2rDtmxlbg==?= <jsjolen () openjdk ! org>
Date:       2023-02-27 11:08:17
Message-ID: WvA6vu5n83QPV8Tm2K-m5m7OKVrzVgRjPJbxEyz2jlQ=.7627ed3f-4493-4d04-8068-b4e1328e3c7e () github ! com
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On Wed, 22 Feb 2023 10:04:05 GMT, Johan Sjölen <jsjolen@openjdk.org> wrote:

> In the 4 pre-defined ChunkPools the pruner save 5 chunks for re-use later in the \
> program. The pruner runs every 5 seconds and saves the first 5 chunks that were \
> last freed and put into the pool. In other words: The lifetime of these 5 chunks \
> are indeterminate, we don't know when these will be freed. This is a problem, \
> because these chunks are allocated with os::malloc(). We might be clobbering our \
> underlying malloc's capacity to shrink its own arena sizes because of the placement \
> of these chunks, and it would be very difficult for us to know whether this is the \
> case. 
> I suggest that we stop saving these 4*5 chunks and always remove all free chunks \
> when cleaning the pools. 
> Passes Arena gtests, running tier1.

This pull request has now been integrated.

Changeset: f2b03f9a
Author:    Johan Sjölen <jsjolen@openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/f2b03f9a2c0fca853211e41a1ddf46195dd56698
                
Stats:     30 lines in 1 file changed: 1 ins; 20 del; 9 mod

8303051: Stop saving 5 chunks in each ChunkPool

Reviewed-by: rehn, coleenp

-------------

PR: https://git.openjdk.org/jdk/pull/12710


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