From 0e06fa476cc160c34ea6f3fef5e8cde06eaac998 Mon Sep 17 00:00:00 2001
From: Graham King <grahamk@nvidia.com>
Date: Fri, 15 Dec 2023 17:28:01 -0500
Subject: [PATCH] feat(subscriber): Reduce default retention to six seconds

`tokio-console`'s default `retain_for` is six seconds. These two values
should match, no point send tokio-console information it's not going to
use.

Fixes the display issue where on initial connect tokio-console
will show hundreds of tasks, and then immediately stop displaying them.

Reduces default memory usage.
---
 console-subscriber/src/lib.rs | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/console-subscriber/src/lib.rs b/console-subscriber/src/lib.rs
index fde18af8d..1cbef9a22 100644
--- a/console-subscriber/src/lib.rs
+++ b/console-subscriber/src/lib.rs
@@ -1,7 +1,4 @@
 #![doc = include_str!("../README.md")]
-use console_api as proto;
-use proto::{instrument::instrument_server::InstrumentServer, resources::resource};
-use serde::Serialize;
 use std::{
     cell::RefCell,
     fmt,
@@ -12,6 +9,10 @@ use std::{
     },
     time::{Duration, Instant},
 };
+
+use console_api as proto;
+use proto::{instrument::instrument_server::InstrumentServer, resources::resource};
+use serde::Serialize;
 use thread_local::ThreadLocal;
 #[cfg(unix)]
 use tokio::net::UnixListener;
@@ -43,14 +44,13 @@ pub(crate) mod sync;
 mod visitors;
 
 pub use aggregator::Aggregator;
+pub use builder::{init, spawn};
 pub use builder::{Builder, ServerAddr};
 use callsites::Callsites;
 use record::Recorder;
 use stack::SpanStack;
 use visitors::{AsyncOpVisitor, ResourceVisitor, ResourceVisitorResult, TaskVisitor, WakerVisitor};
 
-pub use builder::{init, spawn};
-
 use crate::visitors::{PollOpVisitor, StateUpdateVisitor};
 
 /// A [`ConsoleLayer`] is a [`tracing_subscriber::Layer`] that records [`tracing`]
@@ -355,7 +355,8 @@ impl ConsoleLayer {
     /// [environment variable]: `Builder::with_default_env`
     pub const DEFAULT_PUBLISH_INTERVAL: Duration = Duration::from_secs(1);
 
-    /// By default, completed spans are retained for one hour.
+    /// By default, completed spans are retained for six seconds, which
+    /// matches tokio-console's `retain_for` display period.
     ///
     /// Note that methods like [`init`][`crate::init`] and
     /// [`spawn`][`crate::spawn`] will take the value from the
@@ -365,7 +366,7 @@ impl ConsoleLayer {
     /// See also [`Builder::retention`].
     ///
     /// [environment variable]: `Builder::with_default_env`
-    pub const DEFAULT_RETENTION: Duration = Duration::from_secs(60 * 60);
+    pub const DEFAULT_RETENTION: Duration = Duration::from_secs(6);
 
     /// The default maximum value for task poll duration histograms.
     ///