Fix "Long running tasks" logging when dynamic_ui is disabled

docs/notes/2.34.x.md

@@ -26,6 +26,8 @@ Published Pants binaries are now compiled with a new `dist` Cargo profile that e
 
 Pants option config files are now parsed as TOML 1.1 rather than TOML 1.0. This covers `pants.toml` and any other file named by `[GLOBAL].pants_config_files`, the rcfiles named by `[GLOBAL].pantsrc_files` (`/etc/pantsrc`, `~/.pants.rc` and `.pants.rc` by default), and `.toml` files referenced by `@fromfile` option values. Inline tables may now span multiple lines and end with a trailing comma, strings may use the `\e` and `\xHH` escapes, and times may omit their seconds. TOML 1.1 only adds syntax to TOML 1.0, so existing files continue to parse unchanged. TOML files read by backends, such as `pyproject.toml`, are unaffected.
 
+Fixed "Long running tasks:" straggler logging not printing when `dynamic_ui = false`. A memory-leak optimization in [#23485](https://github.com/pantsbuild/pants/pull/23485) disabled the heavy-hitters workunit channel when the dynamic UI was off, but that channel is also used by the non-dynamic-UI `Logging` display to report long-running tasks. This caused CI builds (where `dynamic_ui` defaults to `false`) to lose their heartbeat output and potentially time out.
+
 ### Goals
 
 ### Backends

src/rust/engine/src/session.rs

@@ -159,9 +159,10 @@ impl Session {
         }
         // Only queue workunit messages for consumers which will actually poll for them: the
         // streaming channel is enabled later iff a streaming workunit consumer registers (see
-        // `enable_streaming_workunits`), and the heavy hitters consumer only exists for the
-        // dynamic UI.
-        let workunit_store = WorkunitStore::new(!dynamic_ui, max_workunit_level, false, dynamic_ui);
+        // `enable_streaming_workunits`). The heavy hitters channel is always enabled because it
+        // feeds both the dynamic UI (via `heavy_hitters`) and the non-dynamic-UI straggler
+        // logging (via `straggling_workunits`).
+        let workunit_store = WorkunitStore::new(!dynamic_ui, max_workunit_level, false, true);
         let display = tokio::sync::Mutex::new(SessionDisplay::new(
             &workunit_store,
             core.local_parallelism,