Async Profiler - quick profiling for any application

Are you tired of setting up Java APM agents, configuring some arcane ENV variables (does "org.jboss.logmanager" ring any bells)? Just try Async Profiler ( https://github.com/jvm-profiling-tools/async-profiler ). It is even trivial to use on your already *running* docker images. For example: 

$ kubectl -n my-namespace cp ./async-profiler-2.8-linux-x64.tar.gz my-pod:/root
$ winpty kubectl -n my-namespace exec -it my-pod bash  
root@my-pod:/# cd /root
root@my-pod:~# tar xf async-profiler-2.8-linux-x64.tar.gz
root@my-pod:~# cd async-profiler-2.8-linux-x64
root@my-pod:~/async-profiler-2.8-linux-x64# ./profiler.sh -d 1200 -i 10ms -f profile.html 6
Profiling for 1200 seconds
Done
root@@my-pod:~/async-profiler-2.8-linux-x64# exit
kubectl -n my-namespace cp my-pod:/root/async-profiler-2.8-linux-x64/profile.html ./profile.html

Where "-i 10ms" was how often to run sampling and "6" was the pid of java process (you can check for one with `jps` or plain old `ps`). You can view the resulting flame graph (the local "profile.html" file) in any browser.

Sensible Hibernate batch properties

  <property name="hibernate.jdbc.batch_size" value="30"/>
  <property name="hibernate.order_inserts" value="true"/>
  <property name="hibernate.order_updates" value="true"/>
  <property name="hibernate.jdbc.batch_versioned_data" value="true"/>

Also for postgresql and hibernate < 5.2 add "?reWriteBatchedInserts=true" to connection url.

Checking private (non shared) memory usage for Postgresql connection (PID)

Create function:

 CREATE OR REPLACE FUNCTION pid_mem_usage( pid integer)
 RETURNS integer AS $$
 DECLARE l_command TEXT; res integer;
 BEGIN
  SET client_min_messages = 'error';
  l_command  := ' cat /proc/' || pid || '/smaps | grep "^Private" | awk ''{a+=$2}END{print a * 1024}'' ';
  raise notice '%',l_command;
  execute 'create temp table if not exists z (a int) ';
  execute 'copy z from program ' || quote_literal(l_command);
  execute 'select sum(a) from z' into res;
  execute 'truncate z';
 RETURN res;
 END;
 $$ LANGUAGE plpgsql;

Sample usage:

select pid_mem_usage(pid),pid,usename,backend_start,xact_start,
query from pg_stat_activity  order by 1 desc limit 25;

Based on from https://www.depesz.com/2012/06/09/how-much-ram-is-postgresql-using/

Checking for index bloat in Psotgresql

SELECT
    t.tablename,
    indexname,
    c.reltuples AS num_rows,
    100.0*pg_relation_size(quote_ident(t.schemaname)::text||'.'||quote_ident(indexrelname)::text)/(pg_relation_size(quote_ident(t.schemaname)::text||'.'||quote_ident(t.tablename)::text)+1)as ratio,
    pg_relation_size(quote_ident(t.schemaname)::text||'.'||quote_ident(t.tablename)::text) AS table_size_raw,
    pg_relation_size(quote_ident(t.schemaname)::text||'.'||quote_ident(indexrelname)::text) AS index_size_raw,
    pg_size_pretty(pg_relation_size(quote_ident(t.schemaname)::text||'.'||quote_ident(t.tablename)::text)) AS table_size,
    pg_size_pretty(pg_relation_size(quote_ident(t.schemaname)::text||'.'||quote_ident(indexrelname)::text)) AS index_size,
    CASE WHEN indisunique THEN 'Y'
       ELSE 'N'
    END AS UNIQUE,
    idx_scan AS number_of_scans,
    idx_tup_read AS tuples_read,
    idx_tup_fetch AS tuples_fetched
FROM pg_tables t
LEFT OUTER JOIN pg_class c ON t.tablename=c.relname
LEFT OUTER JOIN
    ( SELECT c.relname AS ctablename, ipg.relname AS indexname, x.indnatts AS number_of_columns, idx_scan, idx_tup_read, idx_tup_fetch, indexrelname, indisunique FROM pg_index x
           JOIN pg_class c ON c.oid = x.indrelid
           JOIN pg_class ipg ON ipg.oid = x.indexrelid
           JOIN pg_stat_all_indexes psai ON x.indexrelid = psai.indexrelid AND (psai.schemaname='public' or psai.schemaname='partitions') )
    AS foo
    ON t.tablename = foo.ctablename
WHERE (t.schemaname='public' or t.schemaname='partitions') 

ORDER BY 5 desc, 6 desc

Compare ratio among partitions of same table to find bloated indexes - the one for current month is always bloated :).

jGitFlow: "CheckoutConflictException: Checkout conflict with files"

This error probably means the master and develop have diverged and develop is behind master. Just merge master to develop and try building again.

Wildfly: NoSuchMethodError: Logger.tracef

When adding Arquillian based integration tests to older projects I often encounter exception:

Exception in thread "Remoting "endpoint" task-4" java.lang.NoSuchMethodError: org.jboss.logging.Logger.tracef(Ljava/lang/String;I)V
        at org.jboss.remotingjmx.VersionedConectionFactory$ClientVersionReceiver.handleMessage(VersionedConectionFactory.java:158)
        at org.jboss.remoting3.remote.RemoteConnectionChannel$5.run(RemoteConnectionChannel.java:456)
        at org.jboss.remoting3.EndpointImpl$TrackingExecutor$1.run(EndpointImpl.java:717)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)

It is caused a mismatch in versions of jboss-logging. The solution is to find additional version:

$ mvn dependency:tree |grep jboss-logging
...

[INFO] +- com.google.guava:guava:jar:18.0:compile
[INFO] +- org.jboss.resteasy:resteasy-client:jar:3.0.19.Final:compile
[INFO] |  +- org.jboss.resteasy:resteasy-jaxrs:jar:3.0.19.Final:compile
[INFO] |  |  +- org.jboss.spec.javax.ws.rs:jboss-jaxrs-api_2.0_spec:jar:1.0.0.Final:compile
[INFO] |  |  +- org.jboss.spec.javax.annotation:jboss-annotations-api_1.2_spec:jar:1.0.0.Final:compile
[INFO] |  |  +- javax.activation:activation:jar:1.1.1:compile
[INFO] |  |  +- commons-io:commons-io:jar:2.1:compile
[INFO] |  |  \- net.jcip:jcip-annotations:jar:1.0:compile
[INFO] |  \- org.jboss.logging:jboss-logging:jar:3.1.4.GA:compile

And to exclude it in pom.xml:

        <dependency>
            <groupId>org.jboss.resteasy</groupId>
            <artifactId>resteasy-client</artifactId>
            <version>3.0.19.Final</version>
            <scope>provided</scope>
            <type>jar</type>
            <exclusions>
                <exclusion>
                    <groupId>org.jboss.logging</groupId>
                    <artifactId>jboss-logging</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

F5 VPN Client under Linux

It looks like many places have outdated or plain wrong instructions about connecting to f5 VPN under Linux is a bit outdated so a quick reminder:

1. Ignore web plugin/extension, it probably won't work anyway under 64 bit browser with disabled NPAPI support
2. download and extract https://vpn.somehost.com/public/download/linux_sslvpn.tgz
3. execute Install.sh
4. f5fpc --start -t vpn.somehost.com