Multi Threading scanning

[astadtla]

I have a use case where I need to scan 2 different scanners at the same time. when I attempt to multi thread pyinsane2 I get the following
TestScanMultiple.txt

error. attached is the python script that generated this error. Any help would be greatly appreciated.

===== RESTART: /home/pi/Documents/LinearBookScanner/TestScanMultiple.py =====

Device Id: 0Device Id: 1

init in thread: 1init in thread: 2

Devices Recieved in thread: 2
Exiting in thread: 2
Exception in thread Thread-1:
Traceback (most recent call last):
File "/home/pi/Documents/LinearBookScanner/TestScanMultiple.py", line 12, in Scan
devices = pyinsane2.get_devices()
File "/usr/local/lib/python3.5/dist-packages/pyinsane2/sane/abstract_proc.py", line 268, in get_devices
for x in remote_do('get_devices', local_only)
File "/usr/local/lib/python3.5/dist-packages/pyinsane2/sane/abstract_proc.py", line 69, in remote_do
result = os.read(fifo_s2c, length)
OSError: [Errno 9] Bad file descriptor

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/usr/lib/python3.5/threading.py", line 914, in _bootstrap_inner
self.run()
File "/usr/lib/python3.5/threading.py", line 862, in run
self._target(*self._args, **self._kwargs)
File "/home/pi/Documents/LinearBookScanner/TestScanMultiple.py", line 16, in Scan
pyinsane2.exit()
File "/usr/local/lib/python3.5/dist-packages/pyinsane2/sane/abstract_proc.py", line 120, in exit
remote_do('exit')
File "/usr/local/lib/python3.5/dist-packages/pyinsane2/sane/abstract_proc.py", line 56, in remote_do
os.write(fifo_c2s, length)
OSError: [Errno 9] Bad file descriptor

[jflesch]

Please call pyinsane2.init() only once from a single thread (for instance in your function Program()). (same goes for pyinsane2.exit()).

[astadtla]

TestScanMultiple.txt
I moved all of the references to pyinsane2 outside of the threads but when i get to the section to start the scan in the any one of the threads:
try:
while True:
scan_session.scan.read()
except EOFError:
pass
i get another error:
===== RESTART: /home/pi/Documents/LinearBookScanner/TestScanMultiple.py =====
Device Id: 0Device Id: 1

Exiting in thread: 1Exiting in thread: 2

Exception in thread Thread-1:
Traceback (most recent call last):
File "/usr/lib/python3.5/threading.py", line 914, in _bootstrap_inner
self.run()
File "/usr/lib/python3.5/threading.py", line 862, in run
self._target(*self._args, **self._kwargs)
File "/home/pi/Documents/LinearBookScanner/TestScanMultiple.py", line 18, in Scan
scan_session.scan.read()
File "/usr/local/lib/python3.5/dist-packages/pyinsane2/sane/abstract_proc.py", line 173, in read
return remote_do('scan_read', self._scanner_name)
File "/usr/local/lib/python3.5/dist-packages/pyinsane2/sane/abstract_proc.py", line 69, in remote_do
result = os.read(fifo_s2c, length)
MemoryError
Exception in thread Thread-2:
Traceback (most recent call last):
File "/usr/lib/python3.5/threading.py", line 914, in _bootstrap_inner
self.run()
File "/usr/lib/python3.5/threading.py", line 862, in run
self._target(*self._args, **self._kwargs)
File "/home/pi/Documents/LinearBookScanner/TestScanMultiple.py", line 18, in Scan
scan_session.scan.read()
File "/usr/local/lib/python3.5/dist-packages/pyinsane2/sane/abstract_proc.py", line 173, in read
return remote_do('scan_read', self._scanner_name)
File "/usr/local/lib/python3.5/dist-packages/pyinsane2/sane/abstract_proc.py", line 70, in remote_do
assert(len(result) == length)
AssertionError

[jflesch]

MemoryError

How much free memory does your device has ? It seems it's running out of memory.

Unfortunately, Pyinsane uses quite a lot of memory to store the chunk of the images. In another bug report, someone reported having issues scanning at 600dpi with only 1GB of ram (raspberry pi).

[astadtla]

I am using a pi, but I have a swap file that adds a GB so 2 in total. I am only scanning at 150 dpi so it should not be to much of a hog at that level. Was the error replicated on your machine with the script I attached in the previous comment?