[EXIM] Limiting the number of simultaneous pipes

I have a pipe based transport that a lot of mail is pushed thru. This
is usually OK. But every once in a while a sudden flood of mail will
arrive for the transport or the command that pipe calls will block
(waiting for a lock to be cleared). This causes a lot of pipe commands
to be running at the same time.

I need some way of limiting the number of simultaneous pipe commands
that can be forked off. I already limit the number of SMTP listeners
and queue handlers and this helps a bit. I'v checked through the
documentation and can't find anything to limit pipe transports in this
way.

Thanks
    Lee
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Lee McLoughlin.                         Phone: +44 171 594 8388
IC-Parc, Imperial College,              Fax:   +44 171 594 8432
South Kensington, London. SW7 2AZ. UK.  Email: lmjm@???

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