Databases
StackOverflow2013
Postsdbo
POGearman + SQLAlchemy - keep losing MySQL thread
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POGearman + SQLAlchemy - keep losing MySQL thread
    primarykey
    data
    text
    <p>I have a python script that sets up several gearman workers. They call into some methods on SQLAlchemy models I have that are also used by a Pylons app.</p> <p>Everything works fine for an hour or two, then the MySQL thread gets lost and all queries fail. I cannot figure out why the thread is getting lost (I get the same results on 3 different servers) when I am defining such a low value for pool_recycle. Also, why wouldn't a new connection be created?</p> <p>Any ideas of things to investigate?</p> <pre><code>import gearman import json import ConfigParser import sys from sqlalchemy import create_engine class JSONDataEncoder(gearman.DataEncoder): @classmethod def encode(cls, encodable_object): return json.dumps(encodable_object) @classmethod def decode(cls, decodable_string): return json.loads(decodable_string) # get the ini path and load the gearman server ips:ports try: ini_file = sys.argv[1] lib_path = sys.argv[2] except Exception: raise Exception("ini file path or anypy lib path not set") # get the config config = ConfigParser.ConfigParser() config.read(ini_file) sqlachemy_url = config.get('app:main', 'sqlalchemy.url') gearman_servers = config.get('app:main', 'gearman.mysql_servers').split(",") # add anypy include path sys.path.append(lib_path) from mypylonsapp.model.user import User, init_model from mypylonsapp.model.gearman import task_rates # sqlalchemy setup, recycle connection every hour engine = create_engine(sqlachemy_url, pool_recycle=3600) init_model(engine) # Gearman Worker Setup gm_worker = gearman.GearmanWorker(gearman_servers) gm_worker.data_encoder = JSONDataEncoder() # register the workers gm_worker.register_task('login', User.login_gearman_worker) gm_worker.register_task('rates', task_rates) # work gm_worker.work() </code></pre>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USocodo
    1. USTony
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POGearman + SQLAlchemy - keep losing MySQL thread
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POGearman + SQLAlchemy - keep losing MySQL thread
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POGearman + SQLAlchemy - keep losing MySQL thread
      1. This table or related slice is empty.
      1. VTUpMod
    1. COAnother thought, are you freeing up the sqlalchemy sessions between tasks or just re-using them?
      singulars
      1. POGearman + SQLAlchemy - keep losing MySQL thread
      1. USDavid
    2. CO@David - no I was not freeing them up, reusing them. Did more digging and found "Can't reconnect until invalid transaction is rolled back" in the logs. So I tried doing a session.rollback() after each job, but that conflicts with the functionality of my one job, which caches the sqlalchemy response object and reuses it on subsequent jobs for big speedups. So what I am trying now is using NullPool - engine = create_engine(sqlachemy_url, poolclass=NullPool) and after each job, calling session.close(). Will know after 24 hours if that is the winning combination.
      singulars
      1. POGearman + SQLAlchemy - keep losing MySQL thread
      1. USTony
    3. COUsing the Nullpool may work ( honestly can't say one way or the other ) but if it doesn't, perhaps a deep clone/copy of the response object will work out ( separating your caching from the DB api ).
      singulars
      1. POGearman + SQLAlchemy - keep losing MySQL thread
      1. USDavid
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload