Fix busy-waiting loops for Server Session / App.java #3016
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iluwatar
requested changes
Jul 23, 2024
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| synchronized (sessions) { | ||
| synchronized (sessionCreationTimes) { |
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Could we use ConcurrentHashMap for sessions and sessionCreationTimes allowing us to remove the need for synchronization blocks?
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| if (entry.getValue().plusMillis(SESSION_EXPIRATION_TIME).isBefore(currentTime)) { | ||
| sessions.remove(entry.getKey()); | ||
| iterator.remove(); |
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Add debug logging for session removal
| } | ||
| }).start(); | ||
| }; | ||
| scheduler.scheduleAtFixedRate(sessionExpirationChecker, 0, SESSION_EXPIRATION_TIME, TimeUnit.MILLISECONDS); |
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We should also shut down the scheduler when the program exits. Something like this:
Runtime.getRuntime().addShutdownHook(new Thread(() -> {
scheduler.shutdown();
try {
if (!scheduler.awaitTermination(60, TimeUnit.SECONDS)) {
scheduler.shutdownNow();
}
} catch (InterruptedException e) {
scheduler.shutdownNow();
}
}));
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What problem does this PR solve?
In the original code, busy waiting is implemented through an infinite loop and Thread.sleep. This method has the following issues:
In the optimized code, busy waiting is replaced by SchechedExecutorService, which executes tasks periodically through event driven methods.