qpull/qpush: progress bar is too verbose and therefore slowdown operation

[Alexander Belchenko]

I'm playing a bit with qpush/qpull and find them very slow comparing to CLI. IMO it's because qsubprocess send all changes of progress bar to frontend window.

Probably we need to reduce size or qty per sec of this messages. Anther option is reworking this progress bar reporting (excluding option of rewriting it in bzrlib :-).

[Alexander Belchenko (bialix)]

I've measured local push of entire branch (creating new branch). qpush is very slow.

qpush: about 7min.
std push: about 2 sec.

Something really going wrong here. We need to rework progress bar system.

[Alexander Belchenko (bialix)]

the numbers above is for pushing qbzr trunk revno.260.

[Alexander Belchenko (bialix)]

For [q]pull qbzr-trunk to empty branch:

qpull: 6m30s
pull: 2sec

[Alexander Belchenko (bialix)]

If I won't manage this slowness I will release 1.0 without this commands (being public at least).

[Alexander Belchenko (bialix)]

I did some experiments and it seems like bottleneck actually inside _report() method of SubprocessProgress. Also there is too much ticks generated per millisecond. So I'd like to thin out messages by some algorithm.

Any ideas?

[Alexander Belchenko (bialix)]

More investigations: commenting out sys.stdin.readline() allow me reach speed of light. So problem probably here. Not in the rate of messages but in blocking sys.stdin read operation.

[Alexander Belchenko (bialix)]

Fixing this by performing blocking read in separate QThread.