The JsonReyclerPools#LockFreePool object takes up a large amount of memory

[zhanbei1]

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Describe the bug

Using com. fasterxml. jackson. core: jackson-databind: 2.17.1 version.
And use the following code:

private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper()
.enable(JsonReadFeature.ALLOW_UNESCAPED_CONTROL_CHARS.mappedFeature())
.enable(JsonReadFeature.ALLOW_LEADING_ZEROS_FOR_NUMBERS.mappedFeature())
.enable(DeserializationFeature.USE_BIG_DECIMAL_FOR_FLOATS);

OBJECT_MAPPER operates on string or Json data.

But this is often my code OOM. Looking at the JVM memory, objects in old_gen keep growing and are hard to gC-drop.(JVM Heap is 2G)

The hprof file generated after OOM occurs, using visualVM: 2.1.8 version, carries on the analysis, discover com. fasterxml. jackson. core. util. JsonReyclerPools# LockFreePool object occupies a lot of memory, and there is some json string type.

May I ask what caused this? Did I use it wrong?

Version Information

jackson-databind:2.17.1

Reproduction

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1. Brief code sample/snippet: include here in preformatted/code section
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// Your code here

Expected behavior

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Additional context

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[cowtowncoder]

The VERY FIRST THING to try is the LATEST PATCH VERSION of minor version you have.
This would be 2.16.2.

This is, in fact, something you should have already tried before filing an issue.

So please try that now.

But also -- just in case -- please double-check you know the exact version of jackson-core you have. Only Jackson 2.17.0 change the default pool to "lockFreePool".

Finally, I will move this issue to its proper place, jackson-core repository where Recycler Pools reside.

[zhanbei1]

The VERY FIRST THING to try is the LATEST PATCH VERSION of minor version you have. This would be 2.16.2.

This is, in fact, something you should have already tried before filing an issue.

So please try that now.

But also -- just in case -- please double-check you know the exact version of jackson-core you have. Only Jackson 2.17.0 change the default pool to "lockFreePool".

Finally, I will move this issue to its proper place, jackson-core repository where Recycler Pools reside.

I'm very sorry, I just got the version number wrong, the version I used is 2.17.1, my comment has been updated. Find a similar issue:FasterXML/jackson-databind#4500

It is not known if this issue has been fixed in a later version

[cowtowncoder]

Issue was indeed fixed by default change in 2.17.1 (as noted in the issue you mention); the problem did affect 2.17.0 (and only 2.17.0).

The only way LockFreePool would be used with 2.17.1 is if application code explicitly configured it to be used.
So I would make sure that the version you use is 2.17.1 (or 2.17.2 which is being released today).
Specifically jackson-core version: jackson-databind does not control RecyclerPool configuration in any way.

If problem seems to occur with jackson-core 2.17.1, also ensure that there is no configuration override to change the recycler pool to LockFreePool.

[zhanbei1]

Issue was indeed fixed by default change in 2.17.1 (as noted in the issue you mention); the problem did affect 2.17.0 (and only 2.17.0).

The only way LockFreePool would be used with 2.17.1 is if application code explicitly configured it to be used. So I would make sure that the version you use is 2.17.1 (or 2.17.2 which is being released today). Specifically jackson-core version: jackson-databind does not control RecyclerPool configuration in any way.

If problem seems to occur with jackson-core 2.17.1, also ensure that there is no configuration override to change the recycler pool to LockFreePool.

Ok, I have understood. Thank you very much for your reply. And I'm going to close this Issue

[cowtowncoder]

Thank you @zhanbei1 ! I hope things resolve as expected, best of luck.