remove allocations round two

[Stebalien]

1. Remove indirection from bsmsg.Entry.
2. Use a pool for AddMessage messages. This showed up in a pprof allocation count profile (top 5) while pinning.

[hannahhoward]

Seems reasonable.

I need to get better with pprof usage so I can discover stuff like this.

[hannahhoward]

Honestly, I was just thinking about this, and I wonder if these messages themselves should just be pass by value. (i.e. make the receiver for the handle function the value) Can you do that? Cause it seems to me you should never actually be modifying the properties of the message (which are effectively just parameters passed over a channel) inside the handle function.

[Stebalien]

Honestly, I was just thinking about this, and I wonder if these messages themselves should just be pass by value. (i.e. make the receiver for the handle function the value) Can you do that? Cause it seems to me you should never actually be modifying the properties of the message (which are effectively just parameters passed over a channel) inside the handle function.

Unfortunately, the channel is taking these by interface; it has to because there are multiple implementations. Whenever any non-pointer value is cast to an interface, it's automatically put on the heap causing an allocation. An alternative is to have a single implementation and put all the logic into that single implementation but, well, that kind of defeats the point of this pattern.

[hannahhoward]

yea makes sense. I read up on the rules of escape analysis and it seems you are right.