feat: add monitoring

[samsja]

WIP, blocked by jina-ai/jina#4526

[numb3r3]

the both monitoring and monitoring_port are redundant. If monitor_port is set, then monitor is enabled, otherwise disabled. Hence, monitoring is not necessary here.

[samsja]

The issue is that there is always a default value pass to monitoring_port, so we do need another parameter to check to say if monitoring is enable or no. What I could do here is just use the default monitoring port so that the yaml does not contain redundant information

[numb3r3]

The default value can be None, am I right?

[numb3r3]

Can we use a global Summary context instance, which can be initialized in the BaseExecutor. Hence, the developer does not need to inject the above codes into the executor implementation. For custome tracking name, we can borrow some ideas from the metric logger from Tensorboard. e.g.,

self.summary.log('text_docs', len(da), ...)
...

[samsja]

There are already some base summary initialize in the BaseExecutor, but here proces text and proces image are specific so this executor so they would always need to be define here
I note for the Tensorboard for custom tracking name.

[hanxiao]

i agree with Felix on this one, I'd prefer:

Best: No change to the executor at all. Injection happens inside the core. Think about Hub Executors, how can we change all of them, especially those are not owned by us.
Okay: injection happens at @requests(..., monitor=True, summary=True)
Bad: need a lot of lines of change like the current PR. This is unacceptable to me, also to all of our Hub Executors.

[samsja]

I might be unclear.

The core will support all bunch of metrics which will be common to all Executor. Like the latency on gateway,head,worker side and the time that the function wrapper by requests takes.
This will be common to all Executor and not a single line of code would be needed on the Executor side.

In addition of that I want to have an extra feature that allow Executor developer to customize and enrich this monitoring by defining by themself new metrics to expose. This is highly relevant for clip as a service as I would like to know how much time is actually used on gpu computation and how much time is used in the text/image preprocessing. The idea with that extra feature is that you can monitoring each sub function that is called inside your request method. And those things can't be abstracted away as it is not common to all executor.

[hanxiao]

this change is not acceptable as I pointed out

[samsja]

Summary of the sync between @numb3r3 and me:

We think about three possible interfaces for exposing the metrics from an Executor:

• Accessing the raw prometheus client.
  • Con: user need to define the summary by themself.
  • Pro: they can leverage the full power of the prometheus client. This solution will stay any way because the two others will rely on it
• Having a decorator to monitor private method
• Having a pytorch-like interface to do the monitoring: ex: self.summary.log('text_docs', len(da), ...)
  • Pro: easier to use as we just need to add one line of code
  • Con: we have to teach a new monitoring interface to the user

I will create a draft feature for each of the proposition so that we can try it out with @numb3r3 and decide what we want to ship at the end

[samsja]

Summary of the sync between @numb3r3 and me:

We think about three possible interfaces for exposing the metrics from an Executor:

* Accessing the raw prometheus client.
  
  * Con: user need to define the summary by themself.
  * Pro: they can leverage the full power of the prometheus client. This solution will stay any way because the two others will rely on it

* Having a decorator to monitor private method

* Having a pytorch-like interface to do the monitoring: ex: `self.summary.log('text_docs', len(da), ...)`
  
  * Pro: easier to use as we just need to add one line of code
  * Con: we have to teach a new monitoring interface to the user

I will create a draft feature for each of the proposition so that we can try it out with @numb3r3 and decide what we want to ship at the end

• raw prometheus (this pr)
• decorator ( feat: add monitoring 2 #704)
• log (feat: add monitoring 3 #705)

@numb3r3 @JoanFM

[numb3r3]

Does the monitor decorator work with arbitrary function? or it can only work with the Executor function (i.e., member function of the executor) whose input and outputs are DocumentArray?

[samsja]

It works with any method of the Executor, it does not require any particular signature. It still need to be a method and not a arbitrary function though, as it needs to access the metrics registry which is store inside the Executor

[codecov]

Codecov Report

Merging #674 (5f6c199) into main (e1acf9a) will increase coverage by 0.30%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #674      +/-   ##
==========================================
+ Coverage   80.56%   80.86%   +0.30%     
==========================================
  Files          16       16              
  Lines        1137     1155      +18     
==========================================
+ Hits          916      934      +18     
  Misses        221      221              

Flag	Coverage Δ
cas	80.86% <100.00%> (+0.30%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
server/clip_server/executors/clip_onnx.py	84.50% <100.00%> (+1.43%)	⬆️
server/clip_server/executors/clip_tensorrt.py	92.85% <100.00%> (+0.85%)	⬆️
server/clip_server/executors/clip_torch.py	85.71% <100.00%> (+1.50%)	⬆️

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