multithreading - Python multiprocessing Pool vs multiprocessing ThreadPool -

-

i have list of image paths want divide between processes or threads each process processes part of list. processing includes loading image disk, computation , return result. i'm using python 2.7 multiprocessing.pool

here's how create worker processes

def processparallel(classifier,path):     files=glob.glob(path+"\*.png")     files_sorted=sorted(files,key=lambda file_name:int(file_name.split('--')[1]))     p = multiprocessing.pool(processes=4,initializer=initializer,initargs=(classifier,))     data=p.map(loadandclassify, files_sorted)     return data

the issue i'm facing when log initialization time in intializer function, came know workers aren't initialized in parallel , rather each worker initialized gap of 5 seconds , here logs reference

2016-08-08 12:38:32,043 - custom_logging - info - worker started 2016-08-08 12:38:37,647 - custom_logging - info - worker started 2016-08-08 12:38:43,187 - custom_logging - info - worker started 2016-08-08 12:38:48,634 - custom_logging - info - worker started

i've tried using multiprocessing.pool.threadpool instead starts workers @ same time.
know how multiprocessing on windows work , have place main guard protect our code spawning infinite processes. issue in case i've hosted script on iis using fastcgi , script isn't main , it's being run fastcgi process (there's wfastcgi.py script responsible that). there main guard inside wfastcgi.py , logs indicate i'm not creating infinite no of processes.

now want know reason behind multiprocessing pool not creating worker threads simultaneously, i'll appreciate help.

edit 1: here's initializer function

def initializer(classifier):     global indexing_classifier     logger.info('worker started')     indexing_classifier=classifier

i had many issues trying run multiprocessing under cgi/wsgi, works fine locally, not on real webservers... isn't compatible. if need multiprocessing, send async jobs off celery.


Comments

Post a Comment

Popular posts from this blog

Spring Boot + JPA + Hibernate: Unable to locate persister -

-
i trying work entity inside request method of spring boot application. entity in project , pom.xml has dependencies it. why error message?: org.hibernate.unknownentitytypeexception: unable locate persister: com.ric.bill.model.bs.par package com.ric.web; import java.util.concurrent.atomic.atomiclong; import javax.persistence.entitymanager; import javax.persistence.persistencecontext; import net.sf.ehcache.cachemanager; import net.sf.ehcache.management.cache; import net.sf.ehcache.management.cachestatistics; import org.hibernate.stat.statistics; import org.springframework.beans.factory.annotation.autowired; import org.springframework.boot.autoconfigure.domain.entityscan; import org.springframework.cache.annotation.enablecaching; import org.springframework.transaction.annotation.enabletransactionmanagement; import org.springframework.transaction.annotation.propagation; import org.springframework.transaction.annotation.transactional; import org.springframework.web.bind.annotati...
Read more

go - Golang: panic: runtime error: invalid memory address or nil pointer dereference using bufio.Scanner -

-
i implementing go program uses bufio.scanner , bufio.writer have packaged code follows package main import ( "fmt" "player/command" "strings" ) func main() { //enter code here. read input stdin. print output stdout commands.scanner.scan() { //scan new line , send comand variable check command exist or not input := strings.split(strings.trim(commands.scanner.text(), " "), " ") command := input[0] if command == "" { fmt.printf("$ %s:", commands.pwd) continue } if !commands.commands[command] { commands.throwerror("cannot recognize input.") } else { commands.execute(command, input[1:], nil) } fmt.printf("$ %s:", commands.pwd) } } i using init.go file in main package follows package main import ( "flag" "player/sourc...
Read more

c - double free or corruption (fasttop) -

-
this code reads null terminated string file (file containing null terminated strings & should provide index wanted string). error: *** error in `./main': double free or corruption (fasttop): 0x090a4a80 *** aborted code: char *tmp_realloc=null; char *sstring=null; int i=1; /*set file pointer point string*/ fseek(fh,index,seek_set); sstring=(char*)malloc(sizeof(char)); if(sstring == null) return null; tmp_realloc=sstring; while( (*(sstring+i-1)=(char)fgetc((file*)fh)) != 0x0 ) { /*reallocate more memory*/ tmp_realloc=(char*)realloc((char*)sstring,++i); /*if not same address copy old new & set old point new*/ if(tmp_realloc != sstring){ strcpy((char*)tmp_realloc,(char*)sstring); free(sstring); sstring=tmp_realloc; } } could tell me pointer causing issue (& reason) ? remove part /*if not same address copy old new & set old point new*/ if(tmp_realloc != sstring){ strc...
Read more