[GROOVY-7673] Remove synchronized methods of groovy.sql.Sql and document it as not thread-safe

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.4.5
• Fix Version/s: 2.5.0-alpha-1
• Component/s: SQL processing
• Labels: breaking
• Assignee: Pascal Schumacher
• Reporter: acefael
• Created: 14/Nov/15 19:53
• Updated: 02/May/17 02:03
• Resolved: 04/Jan/16 18:05

Description

I am using groovy.sql.Sql with a commons dbcp2 BasicDataSource and am encountering a stacktrace as in [2] below. I do create many identical closures with different data, and I pass them all at once to ExecutorService.invokeAll. The closures are all using the same Sql instance.

I believe this is a race condition because it happens only when the database is over a network, and not when the database is local.

To work around I can set Sql.cacheNamedQueries = false. Problem is reliably gone in this case. So I guess the culprit is in [1], with my sql already being cached in namedParamSqlCache, but not yet in namedParamIndexPropCache?

[1] the line in the source code
https://github.com/apache/incubator-groovy/blob/GROOVY_2_4_X/subprojects/groovy-sql/src/main/java/groovy/sql/Sql.java#L4407

[2] the stacktrace

> java.lang.NullPointerException
>       at java.util.ArrayList.<init>(ArrayList.java:168) ~[?:1.8.0]
>       at groovy.sql.Sql.buildSqlWithIndexedProps(Sql.java:4422) ~[groovy-all-2.4.5.jar:2.4.5]
>       at groovy.sql.Sql.checkForNamedParams(Sql.java:4369) ~[groovy-all-2.4.5.jar:2.4.5]
>       at groovy.sql.Sql.getPreparedStatement(Sql.java:4360) ~[groovy-all-2.4.5.jar:2.4.5]
>       at groovy.sql.Sql.getPreparedStatement(Sql.java:4439) ~[groovy-all-2.4.5.jar:2.4.5]
>       at groovy.sql.Sql.execute(Sql.java:2366) ~[groovy-all-2.4.5.jar:2.4.5]
>       at groovy.sql.Sql.execute(Sql.java:2438) ~[groovy-all-2.4.5.jar:2.4.5]
>       at groovy.sql.Sql$execute$1.call(Unknown Source) ~[?:?]
>       at es.acefael.BaseMigration.execute(BaseMigration.groovy:2017) ~[es-acefael-dostuff-SNAPSHOT.jar:?]