Call the offending get_client_config only when required.

[absoludity]

Signed-off-by: Michael Nelson [email protected]

Reduces the proxying of the ~50 API calls (when the go-lang kubeapps-apis initialises its REST mapper) from 4-6s down to a consistent 1.3-1.6s (on my single computer running a cluster including pinniped-proxy).

Description of the change

After more profiling, the remaining offender was the call to create a kube::Client which ranged from 4-100ms (of CPU + interrupts - not sure if there was any I/O) for every single request. So when 50 requests are issued concurrently, it was starving the CPU available (on my single laptop running a cluster etc.).

The call to create the kube::Client is dependent on the target k8s api server only, so it's easy to cache as the number of different results is equal to the number of clusters targeted by Kubeapps. EDIT: Actually, I just realised we may not even need to cache it, since we can simple move where it's evaluated so we only evaluate it when the token was not cached. I'll try that before marking ready.

Benefits

Pinniped proxy handles the 50 concurrent request/responses in a more reasonable time.

Possible drawbacks

Applicable issues

• fixes Improve response times in Kubeapps APIs when using Pinniped-proxy #5407 (finally)

Additional information

Without this change, the main cause of CPU was the call to get_client_config, which then delays all the proxy requests starting:

2022-10-28T01:53:54.191216 [TRACE] - prepare_and_call_pinniped_exchange took 4ms. Used cache?: true. 4ms for get_client_config, 0ms for creating empty cred data, 0ms to fetch the cred.
2022-10-28T01:53:54.291704 [TRACE] - prepare_and_call_pinniped_exchange took 22ms. Used cache?: true. 22ms for get_client_config, 0ms for creating empty cred data, 0ms to fetch the cred.
2022-10-28T01:53:54.470193 [TRACE] - prepare_and_call_pinniped_exchange took 84ms. Used cache?: true. 84ms for get_client_config, 0ms for creating empty cred data, 0ms to fetch the cred.
2022-10-28T01:53:54.585938 [TRACE] - prepare_and_call_pinniped_exchange took 14ms. Used cache?: true. 14ms for get_client_config, 0ms for creating empty cred data, 0ms to fetch the cred.
2022-10-28T01:53:54.674279 [TRACE] - prepare_and_call_pinniped_exchange took 4ms. Used cache?: true. 4ms for get_client_config, 0ms for creating empty cred data, 0ms to fetch the cred.
2022-10-28T01:53:54.683590 [TRACE] - prepare_and_call_pinniped_exchange took 4ms. Used cache?: true. 4ms for get_client_config, 0ms for creating empty cred data, 0ms to fetch the cred.
2022-10-28T01:53:54.769326 [TRACE] - prepare_and_call_pinniped_exchange took 80ms. Used cache?: true. 80ms for get_client_config, 0ms for creating empty cred data, 0ms to fetch the cred.

After the change the call is effectively zero.

2022-10-28T05:28:18.635146 [TRACE] - prepare_and_call_pinniped_exchange took 0ms. Used cache?: true. 0ms for get_client_config, 0ms for creating empty cred data, 0ms to fetch the cred.
2022-10-28T05:28:18.635306 [TRACE] - prepare_and_call_pinniped_exchange took 0ms. Used cache?: true. 0ms for get_client_config, 0ms for creating empty cred data, 0ms to fetch the cred.
2022-10-28T05:28:18.688264 [TRACE] - prepare_and_call_pinniped_exchange took 0ms. Used cache?: true. 0ms for get_client_config, 0ms for creating empty cred data, 0ms to fetch the cred.
2022-10-28T05:28:18.688497 [TRACE] - prepare_and_call_pinniped_exchange took 0ms. Used cache?: true. 0ms for get_client_config, 0ms for creating empty cred data, 0ms to fetch the cred.
2022-10-28T05:28:18.692989 [TRACE] - prepare_and_call_pinniped_exchange took 0ms. Used cache?: true. 0ms for get_client_config, 0ms for creating empty cred data, 0ms to fetch the cred.

[antgamdia]

Awesome; thanks! It is pretty similar to what was happening in kubeaps-apis. Generating the client is an expensive call that requires plenty of calls and we were creating it each time again and again.

[absoludity]

Awesome; thanks! It is pretty similar to what was happening in kubeaps-apis. Generating the client is an expensive call that requires plenty of calls and we were creating it each time again and again.

Yeah - this particular call was a lot less expensive (it's not doing lots of network calls - unlike creating the rest mapper in kubeapps-apis - but when called concurrently 50 times, certainly starving CPU on my system :)

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