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Sam Tunnicliffe commented on CASSANDRA-13291:
---------------------------------------------
This breaks stuff in schema updates when RP is used (not sure how well that's
going to be covered by utest/dtest). To repro, just create a 2 node ccm cluster
with RP, the second node will error out trying to update schema in
{{StorageService::prepareToJoin}}.
I didn't have time to dig into it, but I guess the schema digest calculation is
at fault, M3P isn't affected.
Now, back to that horse I was flogging...
If we've decided that the threadlocal stuff is no longer necessary, I'm not
sure why you moved it from {{FBUtilities}} to {{MD5Digest}} and kept its use by
{{ResultSet}} and {{GuidGenerator}}. If we're sure we don't need it anymore,
lets get rid of it completely. Otherwise, I think it would make sense for
{{RandomPartitioner::hashToBigInteger}} to make use of it, given its hotness.
The main reason I'm interesting is that earlier this week I came across
CASSANDRA-13964, which obviously overlaps with this somewhat.
> Replace usages of MessageDigest with Guava's Hasher
> ---------------------------------------------------
>
> Key: CASSANDRA-13291
> URL: https://issues.apache.org/jira/browse/CASSANDRA-13291
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Michael Kjellman
> Assignee: Michael Kjellman
> Attachments: CASSANDRA-13291-trunk.diff
>
>
> During my profiling of C* I frequently see lots of aggregate time across
> threads being spent inside the MD5 MessageDigest implementation. Given that
> there are tons of modern alternative hashing functions better than MD5
> available -- both in terms of providing better collision resistance and
> actual computational speed -- I wanted to switch out our usage of MD5 for
> alternatives (like adler128 or murmur3_128) and test for performance
> improvements.
> Unfortunately, I found given the fact we use MessageDigest everywhere --
> switching out the hashing function to something like adler128 or murmur3_128
> (for example) -- which don't ship with the JDK -- wasn't straight forward.
> The goal of this ticket is to propose switching out usages of MessageDigest
> directly in favor of Hasher from Guava. This means going forward we can
> change a single line of code to switch the hashing algorithm being used
> (assuming there is an implementation in Guava).
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