ntp.TimeStamp uses incorrect lazy initialisation of static fields
simpleFormatter and utcFormatter
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Key: NET-367
URL: https://issues.apache.org/jira/browse/NET-367
Project: Commons Net
Issue Type: Bug
Reporter: Sebb
Findbugs reports that ntp.TimeStamp uses incorrect lazy initialisation of the
static fields simpleFormatter and utcFormatter.
This is because the static fields are written and read without synchronisation.
One proposed solution is to make the static fields volatile.
The fields are SoftReferences containing SimpleDateFormat instances.
SimpleDateFormat (SDF) is not thread-safe, so when it is used, the code has to
synchronize on the instance.
Are the SoftReferences necessary? Does it really matter if the field cannot be
garbage-collected?
If not, an Init on Demand Holder (IODH) be safer, and would avoid creating the
instance if it was not needed.
Also, is it necessary to use static fields to hold the SimpleDateFormat
instances, given that this requires the synchronisation when using the methods
toUTCString/toDateString?
The other mutable classes in the package are not thread-safe (mutable fields
are not volatile or synch) so overall thread-safety for the package would not
be compromised by using instance fields and removing the SDF synchronisation
and SoftReference.
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