Non-blocking behaviour for python bindings

Status: Beta

Brought to you by: spadix

#48 Non-blocking behaviour for python bindings

Milestone: version_0.10

Status: open-fixed

Owner: spadix

Labels: Scanning/Decoding (27)

Priority: 5

Updated: 2011-02-13

Created: 2011-02-11

Creator: Max

Private: No

As discussed in forum thread: https://sourceforge.net/projects/zbar/forums/forum/664596/topic/4094292

Current python Processor bindings do not support threading.

Discussion

Max - 2011-02-11

Another idea is to use intermediate Video API to achieve non-blocking barcode processing in Python, but it seems to be not implemented in current bindings.

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spadix - 2011-02-13

A fix for this has been pushed to hg (rev 1c14e19910e9).

I did what testing I could, but do not currently have a camera setup, so it would be great if someone could test with video and report back here. Specifically we need tests for:
* setting the processor active and receiving asynchronous calls from the data_handler (single Python thread)
* ensuring that time consuming processor methods (user_wait, process_one, process_image) do not block other threads

Thanks for reporting this!

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spadix - 2011-02-13

status: open --> open-fixed
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Max - 2011-02-13

zbar threading test

zbar_threads_test.py

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- afnfun - 2013-06-17
  
  Hello everybody
  I know that the discussion is old but I have the same case.
  I have tried to use this code with 'wait' mode but the process still blocking other threads!
  only if I add time.sleep(2) inside the process_data() then I got 2 sec unblock time for other processes.
  
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  - afnfun - 2013-06-17
    
    do I need to use a specific version of Zbar ?
    
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Max - 2011-02-13

Thanks, nice work! I updated my test script (attached). There are four modes:

normal mode (just activates processor): zbar_threads_test.py
user wait mode: zbar_threads_test.py wait
process one mode: zbar_threads_test.py one
scan image mode: zbar_threads_test.py image /path/to/image

So far everything looks good - main thread is not stalled and periodically emits alive message. Asynchronous data processing hook is also being called.

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spadix - 2011-02-14

Thanks again for the testing. btw- if you can find a way to automate these tests, I'll certainly add them to the test suite...

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