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https://issues.apache.org/jira/browse/CASSANDRA-17780?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17571867#comment-17571867
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Stefan Miklosovic commented on CASSANDRA-17780:
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This relates to https://issues.apache.org/jira/browse/CASSANDRA-15767, it is
actually same issue.
[~dcapwell] says it is still used for more efficient memory allocation. Is this
still true, David? Hence, I do not think we should remove it but we should
actuall fix this.
> libjemalloc2 is not detected by cassandra script
> ------------------------------------------------
>
> Key: CASSANDRA-17780
> URL: https://issues.apache.org/jira/browse/CASSANDRA-17780
> Project: Cassandra
> Issue Type: Bug
> Components: Local/Scripts
> Reporter: Stefan Miklosovic
> Assignee: Stefan Miklosovic
> Priority: Normal
> Time Spent: 20m
> Remaining Estimate: 0h
>
> I noticed that there was this log message when I started a Cassandra node on
> a machine in AWS on Ubuntu Jelly (22.04).
> {code:java}
> WARN [main] 2022-07-27 11:04:16,731 StartupChecks.java:200 - jemalloc shared
> library could not be preloaded to speed up memory allocations
> {code}
> Hence, I went ahead and I tried to install that package, on 22.04,
> {code:java}
> $ apt search libjemalloc
> Sorting... Done
> Full Text Search... Done
> libjemalloc-dev/jammy 5.2.1-4ubuntu1 amd64
> development files and documentation for jemalloc
> libjemalloc2/jammy,now 5.2.1-4ubuntu1 amd64
> general-purpose scalable concurrent malloc(3) implementation {code}
> So I did apt install libjemalloc2.
> But the problems didnt go away because cassandra script didnt recognised it.
> The value of JVM property the jemalloc startup check is reading from is an
> environment property called CASSANDRA_LIBJEMALLOC (1) which is set by us
> looking into various library paths, trying to find "libjemalloc.so.1"(2). But
> there is no "1" version of it. We have version "2".
> {code:java}
> $ sudo dpkg -L libjemalloc2
> /.
> /usr
> /usr/lib
> /usr/lib/x86_64-linux-gnu
> /usr/lib/x86_64-linux-gnu/libjemalloc.so.2 <---- our tasty libjemalloc
> /usr/share
> /usr/share/doc
> /usr/share/doc/libjemalloc2
> /usr/share/doc/libjemalloc2/README
> /usr/share/doc/libjemalloc2/changelog.Debian.gz
> /usr/share/doc/libjemalloc2/copyright{code}
> (1)
> [https://github.com/apache/cassandra/blob/cassandra-4.0/bin/cassandra#L160]
> (2)
> [https://github.com/apache/cassandra/blob/cassandra-4.0/bin/cassandra#L157]
> I checked what Debian is offering and Bullseye and Buster do not have
> libjemalloc1 anymore, they have version 2, 1 is gone. Strech and Jessie have
> version 1 and not 2 (obviously). Ubuntu Jelly has 2, I am not sure when they
> started to ship 2 instead of 1 but I assume that if a user runs Cassandra on
> "anything recent", this is broken, jemalloc is not used and I think that
> performance can suffer quite significantly.
> This logic is present from 3.0 onwards.
> The patch should fix this and it should take both versions into account. I
> will provide patch with my solution shortly.
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