8291027: Some of TimeZone methods marked 'synchronized' unnecessarily

[turbanoff]

There are 3 methods in java.util.TimeZone which are public static and marked as synchronized:

1. getTimeZone(String)
2. getAvailableIDs(int)
3. getAvailableIDs()

This means it is a bottle neck for the whole VM.
I've checked the implementation and concluded that synchronized is unnecessary.

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Issue

• JDK-8291027: Some of TimeZone methods marked 'synchronized' unnecessarily (Bug - P4)

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[mlbridge]

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• 00: Full (650e141c)

[turbanoff]

BTW can we call ZoneInfoFile.getZoneIds here directly?
ZoneInfo.getAvailableIDs bridge seems redudnant.

[naotoj]

TimeZone is an abstract class, and ZoneInfo is an implementation. So to me, it is clearer to call the overriden method in the implementation even though the reason you mentioned.

[turbanoff]

From OOP point of view - it's strange to call subclass method from a super class.

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[turbanoff]

keep open. Waiting for review

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