feat: add GHC profiling infrastructure via Nix

.gitignore

@@ -5,6 +5,8 @@ dist-newstyle/
 *.hp
 *.prof
 *.hspp
+*.aux
+*.ps
 build.log
 postgres-data/
 grafana-data/

config/dev.yaml

@@ -41,9 +41,9 @@ setup:
 
 peer_manager:
   # Cooldown period after a peer failure before retrying (in seconds)
-  peer_failure_cooldown_seconds: 300
-  max_collector_lifetime_seconds: 3000 # 50 minutes
-  max_concurrent_collectors: 150
+  peer_failure_cooldown_seconds: 60
+  max_collector_lifetime_seconds: 1200 # 20 minutes
+  max_concurrent_collectors: 400
 
 sentry:
   duplicate_blocks:
@@ -106,12 +106,12 @@ quota:
   cleanup_interval: 3600 # 1 hour
 
 orphan_detection:
-  aging_batch_size: 1000
+  aging_batch_size: 5000
 
 block_eviction:
-  eviction_interval_seconds: 3600 # 1 hour
+  eviction_interval_seconds: 300 # 5 minutes
 
 # Cardano node integration configuration
 cardano_node_integration:
   ssh_server_alive_interval_seconds: 60
-  immutable_tip_refresh_seconds: 20
+  immutable_tip_refresh_seconds: 5

docs/profiling.md

@@ -0,0 +1,101 @@
+# Profiling Guide
+
+Quick guide for profiling hoard using GHC's built-in profiling tools.
+
+## Quick Start
+
+### 1. Run with Profiling
+
+```bash
+# Run hoard with profiling enabled
+nix run .#profiling -- +RTS -p -hc -T -RTS your-args-here
+```
+
+This creates:
+- `hoard-exe.prof` - Time and allocation profile
+- `hoard-exe.hp` - Heap profile data
+
+### 2. Visualize Heap Profile
+
+```bash
+# Convert heap profile to PDF and open it
+nix run .#visualize-heap
+```
+
+Opens a PDF showing heap usage over time by cost centre.
+
+## Common Profiling Workflows
+
+### Heap Profiling by Module
+
+For cleaner heap profiles grouped by module instead of cost centre:
+
+```bash
+nix run .#profile-heap-module
+nix run .#visualize-heap
+```
+
+### Time/Allocation Profiling Only
+
+For lightweight profiling without heap data:
+
+```bash
+nix run .#profile-time
+cat hoard-exe.prof
+```
+
+### Custom RTS Flags
+
+Run profiling build directly with your own flags:
+
+```bash
+# Heap profile by type
+nix run .#profiling -- +RTS -hy -p -T -RTS
+
+# Heap profile by closure description
+nix run .#profiling -- +RTS -hd -p -T -RTS
+
+# See all RTS options
+nix run .#profiling -- +RTS --help -RTS
+```
+
+## Available Profiling Apps
+
+| Command | Description |
+|---------|-------------|
+| `nix run .#profiling` | Profiling-enabled executable (pass custom RTS flags) |
+| `nix run .#profile-heap` | Heap profiling by cost centre (detailed but cluttered) |
+| `nix run .#profile-heap-module` | Heap profiling by module (cleaner) |
+| `nix run .#profile-time` | Time and allocation profiling only |
+| `nix run .#visualize-heap` | Convert .hp file to PDF |
+
+## Understanding the Output
+
+### Time Profile (`hoard-exe.prof`)
+
+Shows which functions consume the most time and allocations:
+
+```
+COST CENTRE          %time  %alloc
+fetchBlocks           45.2    38.1
+processBlock          28.3    42.5
+```
+
+### Heap Profile (`hoard-exe.pdf`)
+
+Visual graph showing heap usage over time. Look for:
+- **Steady growth** = possible memory leak
+- **Spikes** = temporary allocations (usually fine)
+- **Flat plateaus** = stable memory usage
+
+## Tips
+
+- Use `-hm` (module) for cleaner graphs than `-hc` (cost centre)
+- Add `-L100` for more detailed heap sampling
+- For concurrency analysis, use `nix run .#profile-eventlog` instead
+- Profile with realistic workloads - toy data won't show real issues
+
+## Further Reading
+
+- [GHC Profiling Guide](https://downloads.haskell.org/ghc/latest/docs/users_guide/profiling.html)
+- [Real World Haskell: Profiling](http://book.realworldhaskell.org/read/profiling-and-optimization.html)

nix/outputs.nix

@@ -75,6 +75,7 @@ let
   secretsApps = import ./secrets.nix { inherit pkgs; };
   cardanoNode = import ./cardano-node.nix { inherit pkgs inputs system; };
   monitoringApps = import ./monitoring.nix { inherit pkgs lib; };
+  profiling = import ./profiling.nix { inherit inputs pkgs; };
 in
 {
   # Expose packages built by haskell.nix
@@ -84,7 +85,9 @@ in
       default = projectFlake.packages."hoard:exe:hoard-exe";
     }
     # Merge in cardano-node packages (mithril-client-cli, etc.)
-    // cardanoNode.packages;
+    // cardanoNode.packages
+    # Merge in profiling package
+    // profiling.packages;
 
   # Development shell
   devShells.default = import ./shell.nix {
@@ -98,6 +101,12 @@ in
 
   # Custom apps
   apps = {
+    # Default app: run hoard executable
+    default = {
+      type = "app";
+      program = "${projectFlake.packages."hoard:exe:hoard-exe"}/bin/hoard-exe";
+    };
+
     # ghcid with multi-repl for all packages and tests
     ghcid-multi = {
       type = "app";
@@ -143,7 +152,9 @@ in
   # Import cardano-node and Mithril apps from separate module
   // cardanoNode.apps
   # Import monitoring apps (Prometheus, Grafana, node_exporter)
-  // monitoringApps.apps;
+  // monitoringApps.apps
+  # Import profiling apps (hoard-profiling, profile-heap, etc.)
+  // profiling.apps;
 
   # Checks
   checks = projectFlake.checks // {