Perf/smoother peer discovery

[asdacap]

• The way new outgoing connection is spawned tend to be spiky, spawning number of connection in bulk. There are also several wait time in an attempt to not spawn too much connection.
• This changes that by having a pool of tasks listening to a blocking channel which is feed by the main peer connection loop. In another word, the peer connection loop is blocked if all thread/task is in use, allowing for an early break if active peer is full. No need to estimate how much you need to push to the threads, which results in much higher thread/task utilization.
• To throttle, an explicit rate limiter is added with a new config --Network.MaxOutgoingConnectPerSec which default to 20, which matches the current peak rate. Unthrottled, peak with 32 thread is about 80 connection per sec.
• The result is, inconsistent as always. But you can set the limit to 999999 and DOS your router if you want.

Run	Time to reach 100 peer (minute)
Before	25
After (10 connect per sec)	25
After (20 connect per sec)	30
Before	40
After (10 connect per sec)	45
After (no limit)	25
After (no limit)	30
After (no limit )	30

Changes

• List the changes

Types of changes

What types of changes does your code introduce?

• Optimization

Testing

Requires testing

• Yes
• No

If yes, did you write tests?

• Yes
• No