58012f85e1
## Proposed Changes
* Modify the `TaskExecutor` so that it spawns a "monitor" future for each future spawned by `spawn` or `spawn_blocking`. This monitor future joins the handle of the child future and shuts down the executor if it detects a panic.
* Enable backtraces by default by setting the environment variable `RUST_BACKTRACE`.
* Spawn the `ProductionBeaconNode` on the `TaskExecutor` so that if a panic occurs during start-up it will take down the whole process. Previously we were using a raw Tokio `spawn`, but I can't see any reason not to use the executor (perhaps someone else can).
## Additional Info
I considered using [`std::panic::set_hook`](https://doc.rust-lang.org/std/panic/fn.set_hook.html) to instantiate a custom panic handler, however this doesn't allow us to send a shutdown signal because `Fn` functions can't move variables (i.e. the shutdown sender) out of their environment. This also prevents it from receiving a `Logger`. Hence I decided to leave the panic handler untouched, but with backtraces turned on by default.
I did a run through the code base with all the raw Tokio spawn functions disallowed by Clippy, and found only two instances where we bypass the `TaskExecutor`: the HTTP API and `InitializedValidators` in the VC. In both places we use `spawn_blocking` and handle the return value, so I figured that was OK for now.
In terms of performance I think the overhead should be minimal. The monitor tasks will just get parked by the executor until their child resolves.
I've checked that this covers Discv5, as the `TaskExecutor` gets injected into Discv5 here:
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|---|---|---|
| .. | ||
| account_utils | ||
| clap_utils | ||
| compare_fields | ||
| compare_fields_derive | ||
| deposit_contract | ||
| directory | ||
| eth2 | ||
| eth2_config | ||
| eth2_interop_keypairs | ||
| eth2_network_config | ||
| eth2_wallet_manager | ||
| fallback | ||
| filesystem | ||
| hashset_delay | ||
| lighthouse_metrics | ||
| lighthouse_version | ||
| lockfile | ||
| logging | ||
| lru_cache | ||
| malloc_utils | ||
| monitoring_api | ||
| sensitive_url | ||
| slot_clock | ||
| target_check | ||
| task_executor | ||
| test_random_derive | ||
| validator_dir | ||
| warp_utils | ||
| README.md | ||
eth2
Common crates containing eth2-specific logic.