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https://issues.apache.org/jira/browse/CASSANDRA-5064?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13531591#comment-13531591
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Jonathan Ellis commented on CASSANDRA-5064:
-------------------------------------------
This is starting to feel fragile, and I've never been a fan of
Table.switchLock/maybeSwitchMemtable in the first place (even though I wrote it
:).
Pushed a different approach to
http://github.com/jbellis/cassandra/branches/5064. The first commit is the
important one: we replace Table.switchLock with reference-counted memtables.
We can then merge DataTracker.[renew|switch]Memtable, change
maybeSwitchMemtable to unconditionally switch (but only flush if there were
updates made), and this problem goes away along with a bunch of other
switchLock-related complexity.
Also suspect that an atomic increment is a performance win over
ReentrantReadWriteLock, which is one of the most heavyweight concurrency
classes.
> 'Alter table' when it includes collections makes cqlsh hang
> -----------------------------------------------------------
>
> Key: CASSANDRA-5064
> URL: https://issues.apache.org/jira/browse/CASSANDRA-5064
> Project: Cassandra
> Issue Type: Bug
> Affects Versions: 1.2.0 beta 3, 1.2.0
> Environment: Ubuntu 12.04 LTS
> 3.2.0-23-virtual
> Reporter: Ryan McGuire
> Assignee: Sylvain Lebresne
> Priority: Critical
> Fix For: 1.2.0
>
> Attachments: 5064.txt
>
>
> Having just installed 1.2.0-beta3 issue the following CQL into cqlsh:
> {code}
> drop keyspace test;
> create keyspace test with replication = {
> 'class': 'SimpleStrategy',
> 'replication_factor': '1'
> };
> use test;
> create table users (
> user_id text PRIMARY KEY,
> first_name text,
> last_name text,
> email_addresses set<text>
> );
> alter table users add mailing_address_lines list<text>;
> {code}
> As soon as you issue the alter table statement cqlsh hangs, and the java
> process hosting Cassandra consumes 100% of a single core's CPU.
> If the alter table doesn't include a collection, it runs fine.
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