python - asyncio catch TimeoutError in Task -


i have asyncio.task need cancel after amount of time. before cancelling, task needs cleanup. according docs, should able call task.cancel or asyncio.wait_for(coroutine, delay) , intercept asyncio.timeouterror in coroutine, following example not working. i've tried intercepting other errors, , calling task.cancel instead, neither have worked. misunderstanding how cancelling task works?

@asyncio.coroutine def totimeout():   try:     = 0     while true:       print("iteration ", i, "......"); += 1       yield asyncio.sleep(1)   except asyncio.timeouterror:     print("timed out")  def main():   #... stuff   yield asyncio.wait_for(totimeout(), 10)   #... more stuff  asyncio.get_event_loop().run_until_complete(main()) asyncio.get_event_loop().run_forever()

the documentation asyncio.wait_for specifies cancel underlying task, , raise timeouterror wait_for call itself:

returns result of future or coroutine. when timeout occurs, cancels task , raises asyncio.timeouterror.

and correct task cancellation can indeed intercepted:

[task.cancel] arranges cancellederror thrown wrapped coroutine on next cycle through event loop. coroutine has chance clean or deny request using try/except/finally.

note docs specify cancellederror thrown coroutine, not timeouterror.

if make adjustment, things work way expect:

import asyncio  @asyncio.coroutine def totimeout():   try:     = 0     while true:       print("iteration ", i, "......"); += 1       yield asyncio.sleep(1)   except asyncio.cancellederror:     print("timed out")  def main():   #... stuff   yield asyncio.wait_for(totimeout(), 3)   #... more stuff  asyncio.get_event_loop().run_until_complete(main())

output:

iteration  0 ...... iteration  1 ...... iteration  2 ...... timed out traceback (most recent call last):   file "aio.py", line 18, in <module>     asyncio.get_event_loop().run_until_complete(main())   file "/usr/lib/python3.4/asyncio/base_events.py", line 316, in run_until_complete     return future.result()   file "/usr/lib/python3.4/asyncio/futures.py", line 275, in result     raise self._exception   file "/usr/lib/python3.4/asyncio/tasks.py", line 238, in _step     result = next(coro)   file "aio.py", line 15, in main     yield asyncio.wait_for(totimeout(), 3)   file "/usr/lib/python3.4/asyncio/tasks.py", line 381, in wait_for     raise futures.timeouterror() concurrent.futures._base.timeouterror

as can see, 'timed out' gets printed before timeouterror raised wait_for.


Comments

Post a Comment

Popular posts from this blog

javascript - Google App Script ContentService downloadAsFile not working -

i have web app developed using google app script htmlservice , html form, populating excel sheet in google drive using spreadsheetapp . , 1 section calling contentservice download data excel file. function doget(e) { // read excel sheet //getappfile(); // render application html template return htmlservice.createtemplatefromfile('index').evaluate() .settitle('go smart') .setsandboxmode(htmlservice.sandboxmode.iframe); } function downloaddoublequatecsvfile() { var sheetid = propertiesservice.getscriptproperties().getproperty('sheetid'); var ss = spreadsheetapp.openbyid(sheetid).getactivesheet(); //var ss = spreadsheetapp.getactivespreadsheet().getactivesheet(); var maxcolumn = ss.getlastcolumn(); var maxrow = ss.getlastrow(); var data = ss.getrange(1, 1, maxrow, maxcolumn).getvalues(); if (data.length > 1) { var csv = ""; (var row = 0; row < data.length; row++) { (var c...
Read more

javascript - Function overwritting -

is there way overwrite function or event handling in function? using addeventlistener, can have many event handlers on element want var test=document.getelementbyid("div"); test.addeventlistener("click",function(){alert("im first");},false); test.addeventlistener("click",function(){alert("im second");},false); // alerts "im first" , after "im second" but if want overwrite function/event example based on client width example this function one() { alert("first"); } function two() { alert("second"); } window.onresize = function() { var test = document.getelementbyid("div"); if (window.innerwidth > 500) { test.onclick = 1 } else { test.onclick = two; } } is possible in javascript? in case use effective little known approach. addeventlistener can accept object property handleevent event handler. in case it's easy overwr...
Read more

c# - Exception when attempting to modify Dictionary -

i creating dictionary manage threads , ran exception when attempt clear dead threads after adding threads dictionary. using system; using system.collections.generic; using system.threading; namespace syscat { public class threadmanager { public static readonly threadmanager globalthreadmanager = new threadmanager( ); /// <summary> /// initializes new instance of <see cref="syscat.threadmanager"/> class. /// </summary> public threadmanager( ) { } /// <summary> /// create new threadmanager threads within basetm , deinitializes basetm /// </summary> public threadmanager( threadmanager basetm ) { this.threads = basetm.threads; basetm.threads.clear( ); } private dictionary<guid,thread> threads = new dictionary<guid, thread>( ); /// <summary> /// attempts obtain unused threadid within ...
Read more