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

Most common (anti-)pattern

I guess that by now everyone knows that Singleton is considered mostly harmful and definitely overused. Many people have said that it hinders testing but there is nothing more convincing that unit test that completes fine on its own but mysteriously fails when whole suite is launched. It looks strange when even after doing reset() and adding new when() rules the mock created by Mockito behaves in wrong way. It is a lot less mysterious when you find a singleton that was injected with mock object on class load and ignores the fact that whole Spring context was created and destroyed multiple times ever since.