Hotfix for resolve many MemoryErrors

[vadimka123]

[ERROR] Exception when performing meta profiling, dumping trace below
Traceback (most recent call last):
  File "/home/vadimka/workspace/Data_Optimization_Prototype/venv/local/lib/python2.7/site-packages/silk/middleware.py", line 110, in _process_response
    collector.finalise()
  File "/home/vadimka/workspace/Data_Optimization_Prototype/venv/local/lib/python2.7/site-packages/silk/collector.py", line 158, in finalise
    query_model = models.SQLQuery.objects.create(**query)
  File "/home/vadimka/workspace/Data_Optimization_Prototype/venv/local/lib/python2.7/site-packages/django/db/models/manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/home/vadimka/workspace/Data_Optimization_Prototype/venv/local/lib/python2.7/site-packages/django/db/models/query.py", line 393, in create
    obj.save(force_insert=True, using=self.db)
  File "/home/vadimka/workspace/Data_Optimization_Prototype/venv/local/lib/python2.7/site-packages/django/utils/decorators.py", line 185, in inner
    return func(*args, **kwargs)
  File "/home/vadimka/workspace/Data_Optimization_Prototype/venv/local/lib/python2.7/site-packages/silk/models.py", line 283, in save
    self.request.save(update_fields=['num_sql_queries'])
  File "/home/vadimka/workspace/Data_Optimization_Prototype/venv/local/lib/python2.7/site-packages/silk/models.py", line 167, in save
    Request.garbage_collect(force=False)
  File "/home/vadimka/workspace/Data_Optimization_Prototype/venv/local/lib/python2.7/site-packages/silk/models.py", line 149, in garbage_collect
    if not requests or len(requests)-1 < target_count:
  File "/home/vadimka/workspace/Data_Optimization_Prototype/venv/local/lib/python2.7/site-packages/django/db/models/query.py", line 258, in __nonzero__
    return type(self).__bool__(self)
  File "/home/vadimka/workspace/Data_Optimization_Prototype/venv/local/lib/python2.7/site-packages/django/db/models/query.py", line 254, in __bool__
    self._fetch_all()
  File "/home/vadimka/workspace/Data_Optimization_Prototype/venv/local/lib/python2.7/site-packages/cacheops/query.py", line 273, in _fetch_all
    return self._no_monkey._fetch_all(self)
  File "/home/vadimka/workspace/Data_Optimization_Prototype/venv/local/lib/python2.7/site-packages/django/db/models/query.py", line 1102, in _fetch_all
    self._result_cache = list(self._iterable_class(self))
  File "/home/vadimka/workspace/Data_Optimization_Prototype/venv/local/lib/python2.7/site-packages/django/db/models/query.py", line 53, in __iter__
    results = compiler.execute_sql(chunked_fetch=self.chunked_fetch)
  File "/home/vadimka/workspace/Data_Optimization_Prototype/venv/local/lib/python2.7/site-packages/silk/sql.py", line 45, in execute_sql
    return self._execute_sql(*args, **kwargs)
  File "/home/vadimka/workspace/Data_Optimization_Prototype/venv/local/lib/python2.7/site-packages/django/db/models/sql/compiler.py", line 876, in execute_sql
    cursor.execute(sql, params)
  File "/home/vadimka/workspace/Data_Optimization_Prototype/venv/local/lib/python2.7/site-packages/django/db/backends/utils.py", line 80, in execute
    return super(CursorDebugWrapper, self).execute(sql, params)
  File "/home/vadimka/workspace/Data_Optimization_Prototype/venv/local/lib/python2.7/site-packages/django/db/backends/utils.py", line 65, in execute
    return self.cursor.execute(sql, params)
  File "/home/vadimka/workspace/Data_Optimization_Prototype/venv/local/lib/python2.7/site-packages/django/db/backends/mysql/base.py", line 101, in execute
    return self.cursor.execute(query, args)
  File "/home/vadimka/workspace/Data_Optimization_Prototype/venv/local/lib/python2.7/site-packages/MySQLdb/cursors.py", line 205, in execute
    self.errorhandler(self, exc, value)
  File "/home/vadimka/workspace/Data_Optimization_Prototype/venv/local/lib/python2.7/site-packages/MySQLdb/connections.py", line 36, in defaulterrorhandler
    raise errorclass, errorvalue
MemoryError

[avelis]

@vadimka123 Thanks for making a PR. If you could address the PR's I could take a look and potentially merge in this change.

[vadimka123]

@avelis, how to do this?

[avelis]

You can see the build failure here:
https://travis-ci.org/jazzband/django-silk/builds/425169004?utm_source=github_status&utm_medium=notification

======================================================================
FAIL: test_greedy_garbage_collect (tests.test_models.RequestTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/travis/build/jazzband/django-silk/project/tests/test_models.py", line 158, in test_greedy_garbage_collect
    models.Request.garbage_collect(force=True)
  File "/home/travis/build/jazzband/django-silk/project/silk/models.py", line 152, in garbage_collect
    cls.objects.all().order_by('id')[:records_count_to_delete].delete()
  File "/home/travis/virtualenv/python3.4.6/lib/python3.4/site-packages/django/db/models/query.py", line 598, in delete
    "Cannot use 'limit' or 'offset' with delete."
AssertionError: Cannot use 'limit' or 'offset' with delete.

@vadimka123 It looks like it doesn't like a delete method from a slice.

[avelis]

@vadimka123 Getting closer.
https://travis-ci.org/jazzband/django-silk/builds/469903442?utm_source=github_status&utm_medium=notification
Looks like MySQL doesn't support certain queries the tests are running.

[xrmx]

@vadimka123 your issue should be fixed in master, i think you can close this.