Previously, when DevTools was restarting the application it would
use reflection to run all of the JVM's shutdown hooks. This was done
to close any SpringApplications' application contexts. Unfortunately,
it had the unwanted side-effect of running other shutdown hooks as
well.
The other shutdown hooks were often written with the, entirely
reasonable, expectation that they would only be called when the JVM
was shutting down. Calling them at another time could leave the
hook's library in an unexpected state. One such example is Log4J2
which was worked around in aaae4aa3 (see gh-4279). Another is the
problem with Eureka (see gh-4097). There's no work around for this
problem, even with reflective hackery, hence the change being made
here.
This commit updates the Restarter so that shutdown hooks are no longer
called during a restart. This removes the chance of a restart having
the unwanted side-effect of leaving a third-party library in a broken
state. RestartApplicationListener now prepares the Restarter with the
root application context, and the Restarter then closes it as part of
the restart. The changes have been tested with an application that
uses a single context and an application with a context hierarchy.
Closes gh-4097
Previously an in-memory database that wasn’t pooled (an
EmbeddedDatabase) would be shutdown when the context restarted, but
an in-memory database wrapped in a connection pool was not. This meant
that the former would be be wiped clean after each restart, whereas the
latter would not. In addition to being inconsistent, this also
caused problems with schema.sql and data.sql scripts when using
DevTools. If you were using an in-memory database wrapped in a
connection pool, a failure may occur during a restart as the scripts
were not being run against in clean database.
This commit adds an auto-configured bean to DevTools that, when the
context is being closed, will execute “SHUTDOWN” if it identifies that
the DataSource is not an EmbeddedDatabase and is for an in-memory
database.
Closes gh-4699
Allow `META-INF/spring-devtools.properties` files to be used by
application developers to declare is specific jars should be included
or excluded from the RestartClassLoader.
A typical example where this might be used is a company that develops
it's own set of internal JARs that are used by developers but not
usually imported into their IDE.
See gh-3316
During a restart, the Restarter runs all registered shutdown hooks. This
breaks Log4J2 as it leaves it in a shutdown state that leaves logging
switched off such that no output it produced when the application starts
up again.
This commit introduces a new RestartListener abstraction.
RestartListeners are notified prior to the application being restarted.
A Log4J2-specific implementation is provided that prepares Log4J2 for
restart by removing any shutdown callbacks from its shutdown callback
registry. This prevents the restart from shutting down Log4J2, ensuring
that it still functions when the application restarts.
Closes gh-4279
Prior to this commit, the devtools used bean factory post processors to
configure the environment with custom, development-time properties. This
meant that the environment was configured as part of the application
context being refreshed. Crucially, this happened after any property
conditions were evaluated making it impossible for the devtools to
change the default auto-configuration behaviour for a bean or
configuration class that was conditional on a property.
This commit moves the configuration of the environment into an
ApplicationListener that listens for the
ApplicationEnvironmentPreparedEvent which is published as soon as the
Environment has been prepared and before the application context is
refreshed.
Closes gh-3726
