column-pager: log spill mechanism resolution for debugging

Author: DAlperin

src/compute/src/compute_state.rs

@@ -342,7 +342,7 @@ impl ComputeState {
             let total = usize::cast_lossy(f64::cast_lossy(mem_limit) * fraction).max(128 * MIB);
 
             if use_pool && apply_pool_config(enabled, total) {
-                debug!(
+                info!(
                     enabled,
                     fraction,
                     mem_limit,
@@ -362,7 +362,7 @@ impl ComputeState {
                     Backend::Swap
                 };
 
-                debug!(
+                info!(
                     enabled,
                     ?backend,
                     ?codec,

src/storage/src/storage_state.rs

@@ -854,6 +854,10 @@ impl<'w> Worker<'w> {
 
                     let enabled = ENABLE_UPSERT_PAGED_SPILL
                         .get(self.storage_state.storage_configuration.config_set());
+                    info!(
+                        worker = self.timely_worker.index(),
+                        enabled, "upsert stash pager: applying gate",
+                    );
                     crate::upsert::upsert_stash_pager::set_enabled(enabled);
                 }
             }

src/timely-util/src/column_pager.rs

@@ -428,14 +428,18 @@ pub fn global_pager() -> ColumnPager {
 /// [`apply_tiered_config`]), so a consumer that captured a pager before a
 /// mechanism flip keeps its old one until it next calls here.
 pub fn shared_pager(enabled: bool) -> ColumnPager {
+    let pool_mode = POOL_MODE.load(std::sync::atomic::Ordering::Relaxed);
     if !enabled {
+        tracing::info!(enabled, pool_mode, "shared column pager resolved: disabled");
         return ColumnPager::disabled();
     }
-    if POOL_MODE.load(std::sync::atomic::Ordering::Relaxed) {
+    if pool_mode {
         if let Some(pool) = global_pool() {
+            tracing::info!(enabled, pool_mode, "shared column pager resolved: pool");
             return ColumnPager::pooled(pool);
         }
     }
+    tracing::info!(enabled, pool_mode, "shared column pager resolved: tiered");
     #[allow(clippy::clone_on_ref_ptr)]
     let dyn_policy: Arc<dyn PagingPolicy> = TIERED_POLICY.clone();
     ColumnPager::new(dyn_policy)