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https://issues.apache.org/jira/browse/CASSANDRA-5064?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13532335#comment-13532335
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Jonathan Ellis commented on CASSANDRA-5064:
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bq. Do we agree that it doesn't do the "change maybeSwitchMemtable to
unconditionally switch"?
Here's the new core of switchMemtable:
{code}
. for (ColumnFamilyStore cfs : concatWithIndexes())
{
Memtable mt = cfs.data.switchMemtable();
if ((!mt.isClean()))
memtables.add(mt);
}
{code}
bq. I see nothing that prevents flushing the same memtable multiple times.
What prevents it is that DataTracker.switchMemtable is atomic and will only
return a given memtable once. (So, if we have a whole bunch of threads calling
forceFlush at once, we'll probably switch out a few empty ones, but that is the
end of the extra work we do.)
bq. for counter this is a bug
Ugh, counters again. Have to think about this.
bq. I also don't think using reference counting really makes this issue simpler.
I do. :) We're net -120 lines of fairly tricky code. We've had multiple bugs
from not dealing with switchlock correctly (CASSANDRA-3712 and the flushing
code from CASSANDRA-3411, off the top of my head).
bq. I'm really doubtful that changing such an important piece of code just
before a release is a good idea
I'll buy that.
> '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, 5064-v2.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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