python - Peewee python2.7 database locked error -

i have script queries on database "blogs" , each blog, starts thread query rss address , check new posts , record them on database. initially, running script maximum of 2 parallel threads (retrieving information rss of @ least 2 blogs @ same time) , then, started getting "database locked error", reduced one, , still error.

for database connection , orm using peewee 2.7.4 this:

from peewee import * playhouse.sqlite_ext import sqliteextdatabase  db = sqliteextdatabase(app_dir + '/ml.db')  class basemodel(model):     class meta:        database = db  class blog(basemodel):      (...)  class post(basemodel):      (...) 

so, starting script does:

def start():     global active_threads, max_threads     blogs = blog.select().where(block.active=1)     blog in blogs:         while active_threads == max_threads:             print 'max number of threads %d reached. zzzz' % max_threads             time.sleep(1)         blog.processing=1         blog.save()          active_threads += 1          th = threading.thread(target=process_blog, args=(blog,))         th.daemon = true         th.start()  def process_blog(blog):     globals active_threads     get_new_posts_url_for_blog(blog) # here post records created downloaded=0     posts = post.select().where(post.downloaded = 0)     post in posts:         content = get_content_for_post(post.url)         post.content = content         post.downloaded = 1         post.save() #this database locked error thrown :(      active_threads -= 1 

this simplified version of script, of course, , @ first loop on "posts", following error on post.save():

file "/home/thilux/virtual_envs/ptmla/local/lib/python2.7/site-packages/peewee.py", line 4573, in save rows = self.update(**field_dict).where(self._pk_expr()).execute() file "/home/thilux/virtual_envs/ptmla/local/lib/python2.7/site-packages/peewee.py", line 3013, in execute return self.database.rows_affected(self._execute()) file "/home/thilux/virtual_envs/ptmla/local/lib/python2.7/site-packages/peewee.py", line 2555, in _execute return self.database.execute_sql(sql, params, self.require_commit) file "/home/thilux/virtual_envs/ptmla/local/lib/python2.7/site-packages/peewee.py", line 3366, in execute_sql self.commit() file "/home/thilux/virtual_envs/ptmla/local/lib/python2.7/site-packages/peewee.py", line 3212, in __exit__ reraise(new_type, new_type(*exc_args), traceback) file "/home/thilux/virtual_envs/ptmla/local/lib/python2.7/site-packages/peewee.py", line 3359, in execute_sql cursor.execute(sql, params or ()) operationalerror: database locked 

keep in mind now, running max_threads=1 there 1 blog being processed @ time. bothers me on first runs, run max_threads=2 , go way through, fine. error started few days later, don't know if maybe on blogs select, on main thread, things locked (maybe select attached , have detach'em somehow). please me this? small process , not change database engine, , see performance benefits, crucial, running in @ least 2 threads in parallel.

your appreciated.

thank you, ts

try wrapping writes atomic() context manager.