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Re: Please help with Threading

 
 
Cameron Simpson
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      05-20-2013
On 20May2013 10:53, Carlos Nepomuceno <(E-Mail Removed)> wrote:
| I just got my hands dirty trying to synchronize Python prints from many threads.
| Sometimes they mess up when printing the newlines.
| I tried several approaches using threading.Lock and Condition.
| None of them worked perfectly and all of them made the code sluggish.

Show us some code, with specific complaints.

Did you try this?

_lock = Lock()

def lprint(*a, **kw):
global _lock
with _lock:
print(*a, **kw)

and use lprint() everywhere?

For generality the lock should be per file: the above hack uses one
lock for any file, so that's going to stall overlapping prints to
different files; inefficient.

There are other things than the above, but at least individual prints will
never overlap. If you have interleaved prints, show us.

| Is there a 100% sure method to make print thread safe? Can it be fast???

Depends on what you mean by "fast". It will be slower than code
with no lock; how much would require measurement.

Cheers,
--
Cameron Simpson <(E-Mail Removed)>

My own suspicion is that the universe is not only queerer than we suppose,
but queerer than we *can* suppose.
- J.B.S. Haldane "On Being the Right Size"
in the (192 book "Possible Worlds"
 
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