Purpose: Tells AutoPatch to apply a patch regardless of whether the Oracle Applications system is in maintenance mode. AutoPatch aborts the patching session if maintenance mode is disabled and the options=hotpatch command is not used."
Now whether you need to bounce or not still depends on the patch you are applying.
WHEN HOT PATCH CAN BE USED :
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If the patch is small and only affects a limited number of objects such as an updated form or report or perhaps just a database
package or two, then you could *potentially* apply the patch to a live environment.
WHEN HOT PATCH CAN **NOT** BE USED :
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> Patches that make changes to executables,
> Makes numerous database changes,
> has new Java code,
> Adds/changes seed data,
> Large patches, etc. could not realistically be applied to a live environment.
Depending on what's being changed, then you could need to bounce the Concurrent Manager, forms server, web server, database, etc. for changes to take effect.
Some changes (like a database change) would take effect immediately though, and lead to possible corruption due to a
mismatch in code.
Your environment would not have the complete fix until it was bounced. Even with using the "hotpatch" flag, it still all depends on
what the patch itself is changing on whether you need to bounce or not. or anything more than a one-off patch in which I know exactly what's being changed, I would not apply patches to a live environment, especially production.
You can also check with Oracle Support to see their official take on things, but from what I've seen from them, they would tell you the same thing as above.