RetryParams
is provided by the App Engine client library for Cloud Storage contained
in src/cloudstorage
. This class lets you change default settings used to
handle timeouts and retries.
Introduction
The App Engine client library for Cloud Storage uses default settings for handling
timeouts and retries during attempts to contact Google Cloud Storage servers.
This class allows you to change those settings, either on an application-wide
basis, or for a specific invocation of a library
function (copy2
, delete
, listbucket
, open
, stat
). You need change only
the specific setting you are interested in, as all other settings are retained
unless explicitly overwritten. Each RetryParams
instance is unique per thread
and per request.
To change a default setting application-wide, you create a RetryParams
object, specify whatever settings you wish to change, and supply this object to
the cloudstorage.set_default_retry_params()
function as follows:
my_default_retry_params = cloudstorage.RetryParams(initial_delay=0.2,
max_delay=5.0,
backoff_factor=2,
max_retry_period=15)
cloudstorage.set_default_retry_params(my_default_retry_params)
To change default settings for a specific function invocation only, create
a RetryParams
object and supply it directly to the function in its
retry_params
parameter, as follows:
write_retry_params = cloudstorage.RetryParams(backoff_factor=1.1)
gcs_file = cloudstorage.open(filename,
'w',
content_type='text/plain',
options={'x-goog-meta-foo': 'foo',
'x-goog-meta-bar': 'bar'},
retry_params=write_retry_params)
This has no effect on the default settings used by the app or by other function invocations.
Instance properties
A RetryParams
instance has the following properties:
- initial_delay
- The number of seconds to delay before a retry. Default is
0.1
. Delay helps distribute load at the Google Cloud Storage server. - backoff_factor
- The exponential back-off multiplier, used to determine optimal processing
rate. Default is
2.0
. For a description and recommendations for setting this value, see the Google Cloud Storage documentation on backoff. - max_delay
- The maximum number of seconds to wait between retries. Default is
10.0
. - min_retries
- The minimum number of times to retry. Default is
3
. - max_retries
- The maximum number of times to retry. Set this value to 0 if
you don't want any retries. Default is
6
. - max_retry_period
- The maximum number of seconds that can be spent on all retries of a
given request. Default is
30.0
. Retry stops when this period passed ANDmin_retries
has been attempted. - urlfetch_timeout
- The number of seconds to wait for UrlFetch to contact the
Google Cloud Storage servers before returning a timeout error. By default,
this is set to
None
, which means use the default UrlFetch deadline, which is five seconds. You can set this to any value up to a maximum of 60 seconds.