Is is safe to use HSQLDB for production? (JBoss AS5.1)

The JBoss developers warn against the use of HSQLDB as a persistent storage (see JBoss wiki). I am confused though, because HSQLDB appears to be used heavily in production.

Especially, the above mentioned page seems to warn against the use of HSQLDB e开发者_JAVA技巧ntirely and not against the use in conjunction with JBoss.

Is it still not recommendable to use HSQLDB in JBoss (particularly, the bundled default datasource in Community JBoss 5.1)?

*:We plan to use it in in-memory mode.

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If your own link doesn't convince you, then consider that using it in in-memory mode can lead to undesirable effects when JMS queues get backed up -- JBoss will start trying to persist the messages to the backing store to free heap space, but that won't actually help. Soon, you're spinning in GC or throwing OOM exceptions.