perf(cli): ship mimalloc in the production feature

crates/tracedecay-cli/Cargo.toml

@@ -74,7 +74,7 @@ hotpath-cpu = [
     "hotpath/hotpath-cpu",
 ]
 hotpath-mcp = ["hotpath", "hotpath/hotpath-mcp"]
-production = ["tracedecay/production"]
+production = ["tracedecay/production", "alloc-mimalloc"]
 # Opt-in tiered graph storage; not part of `production`.
 graph-disk-tier = ["tracedecay/graph-disk-tier"]
 token-counting = ["tracedecay/token-counting"]
@@ -119,10 +119,18 @@ lang-fsharp = ["tracedecay/lang-fsharp"]
 lang-quint = ["tracedecay/lang-quint"]
 lang-toml = ["tracedecay/lang-toml"]
 lang-lean = ["tracedecay/lang-lean"]
-# Opt-in global allocators for the shipped binary (daemon included). The
-# default stays glibc malloc; selecting an allocator is a deploy decision.
-# When several allocator features are enabled at once (e.g. `--all-features`),
-# main.rs resolves them by fixed precedence instead of failing the build:
+# Global allocators for the shipped binary (daemon included). `production`
+# ships mimalloc: glibc malloc has no setting that fits a daemon indexing on
+# dozens of worker threads. Measured on beta.41 on a 96-core host warming 12
+# projects: with MALLOC_ARENA_MAX=2, 60% of daemon CPU was the two arena
+# locks; with the cap removed, 747 arenas held 14 GB of freed-but-retained
+# heap out of 18 GB RSS, and because admission trusts measured RSS the graph
+# could never activate again after one peak. mimalloc has per-thread heaps
+# without the lock and purges freed segments, so RSS follows live data (peak
+# unchanged, ~18 GB during the warm; back to 8-13 GB between phases) and the
+# resident-memory refusal clears on its own. When several allocator features
+# are enabled at once (e.g. `--all-features`), main.rs resolves them by fixed
+# precedence instead of failing the build:
 # hotpath-alloc (measurement) > alloc-jemalloc > alloc-mimalloc > system.
 #
 # alloc-jemalloc turns jemalloc background purge threads on by default:

crates/tracedecay-cli/src/main.rs

@@ -18,12 +18,12 @@ static HOTPATH_ALLOCATOR: hotpath::CountingAllocator = hotpath::CountingAllocato
 // Opt-in allocator features (see Cargo.toml). Exactly one global allocator
 // may exist per binary, so overlapping selections resolve by fixed precedence
 // rather than a compile error: hotpath-alloc's counting allocator wins in
-// measurement builds, then jemalloc, then mimalloc. The default build keeps
-// the system allocator (glibc malloc on Linux). The installed service unit
-// must not cap glibc's arenas: `MALLOC_ARENA_MAX=2` once did, to bound
+// measurement builds, then jemalloc, then mimalloc. `production` selects
+// mimalloc (see Cargo.toml for the measurements); only a build that opts out
+// of it keeps the system allocator, and the installed service unit must not
+// cap glibc's arenas either way: `MALLOC_ARENA_MAX=2` once did, to bound
 // retained memory, and put 60% of a 20-worker daemon's CPU into two arena
-// locks (perf on beta.41: every wait was `__lll_lock_wait_private` under
-// ordinary Vec/String growth) while RSS still reached 15 GB.
+// locks while RSS still reached 15 GB.
 #[cfg(all(feature = "alloc-jemalloc", not(feature = "hotpath-alloc")))]
 #[global_allocator]
 static JEMALLOC_ALLOCATOR: tikv_jemallocator::Jemalloc = tikv_jemallocator::Jemalloc;