RFR: 8042810: (s) hgforest: some shells run read in sub-shell and can't use fifo

[Mike Duigou]

On May 8 2014, at 22:35 , Chris Hegarty <chris.hegarty at oracle.com> wrote:

> Looks fine to me Mike.
> 
> Trivially while you are there (not related to your changes), or i can do it separately, --sequentially now runs with up to two parallel commands. 

Ah sorry, I know why that is. It is due to shell having less-than but no less-than-or-equal-to operator. I can fix this easily and will do so before pushing. It's simply a matter of reducing at_a_time to 0. This will look odd but solve the problem.

> 
> -Chris
> 
>> On 9 May 2014, at 03:19, Mike Duigou <mike.duigou at oracle.com> wrote:
>> 
>> Hello all;
>> 
>> This issue is a follow-on bug fix to JDK-8041151 (Improve hgforest.sh concurrency). That changeset introduced use of fifos for monitoring sub-shell completion and included an alternative implementation for configurations which did not properly support fifos. This changeset detects another unsupported configuration, older shells which run the "read" command using a sub-shell.
>> 
>> I've tested the change on Solaris 10u11, Solaris 11u1, Ubuntu Linux 13.10 x64, MacOS 10.9. Of these only the Bash 3.2 shell on Solaris 10u11 does not support FIFOs. I have not tested this specific change on Cygwin as FIFOs were already disabled on Cygwin.
>> 
>> https://bugs.openjdk.java.net/browse/JDK-8042810
>> http://cr.openjdk.java.net/~mduigou/JDK-8042810/0/webrev/
>> 
>> Mike