[jira] [Created] (CASSANDRA-17780) libjemalloc2 is not detected by cassandra script

["Stefan Miklosovic (Jira)" <ji...@apache.org>]

Stefan Miklosovic created CASSANDRA-17780:
---------------------------------------------

             Summary: 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


I noticed that there was this log message when I started a Cassandra node on a machine in AWS on Ubuntu Jelly (22.04).

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 thing 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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