AsyncToSync freezes threads for really long time on channel_layer.group_add

Im trying to make the async call to group_add synchronous like in the docs … but when I do the whole request cycle freezes and doesn’t let me take other requests.

 39     def make_sub(info, gid):
 40         inst = relay.Node.get_node_from_global_id(info, gid)
 41         try:
 42             gp_name = 'gqp.{0}-updated.{1}'.format(str.lower(inst.__class__.__name__), inst.pk)
 43             # Group(gp_name).add(info.context.reply_channel)
 44             # info.context.channel_session['Groups'] = ','.join( (gp_name, info.context.channel_session['Groups']))
 45             __import__('pdb').set_trace()
 46  ->         AsyncToSync(channel_layer.group_add)(
 47                     gp_name,
 48                     info.context['reply_channel']
 49                 )
 50             if 'Groups' in info.context.scope['session']:
 51                 info.context.scope['session']['Groups'] = ','.join((gp_name, info.context.scope['session']['Groups']))
 52         except:
 53             pass
 54         return iter([inst])
(Pdb) channel_layer.group_add
<bound method RedisChannelLayer.group_add of <channels_redis.core.RedisChannelLayer object at 0x7fb322c835f8>>
(Pdb) gp_name
'gqp.product-updated.1'
(Pdb) info.context['reply_channel']
'specific..YgcGdjPn!HfWtmWwbyFou'
(Pdb) inst
<Product: atests>
(Pdb) AsyncToSync
<class 'asgiref.sync.AsyncToSync'>
(Pdb) c

[andrewgodwin]

The key thing to remember is:

• Never call a sync function from an async function without await sync_to_async(function)(args, ...)
• Never call an async function from a sync function without async_to_sync(function)(args, ...)

[andrewgodwin]

Oh, in the code example you posted. If you’re in an AsyncConsumer already then just convert all the functions to async functions (async def) then await them.

Or, if you want to keep those functions sync, use sync_to_async when you switch from an async def to calling a def, e.g. result = await sync_to_async(schema.execute)(self.query, ...)