Stefan Miklosovic created CASSANDRA-17780:
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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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