RFR: 8255405: sun/net/ftp/imp/FtpClient uses SimpleDateFormat in not thread-safe manner [v3]

[Chris Hegarty]

On Wed, 28 Oct 2020 15:25:06 GMT, Igor Ignatyev <iignatyev at openjdk.org> wrote:

>> Hi all,
>> 
>> could you please review this small and trivial fix?
>> 
>> `sun/net/ftp/imp/FtpClient::dateFormats` is an array of `SimpleDateFormat` which are shared among all instances of `FtpClient`. the fact that `SimpleDateFormat` isn't thread-safe renders`FtpClient` to be non-thread-safe as well. the patch makes the only usage of `dateFormats` array, `parseRfc3659TimeValue` method, `synchronized`.
>> 
>> the problem was reported in #776
>> 
>> Thanks,
>> -- Igor
>
> Igor Ignatyev has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - use UTC TZ for RFC3659_DATETIME_FORMAT
>  - run TestFtpTimeValue with different user.timezone

Marked as reviewed by chegar (Reviewer).

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PR: https://git.openjdk.java.net/jdk/pull/867