llo: perform an vss alloc at plugin initialization to avoid GC overhead (#187)

Author: brunotm

llo/plugin.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	sync "sync"
 	"time"
 
 	"github.com/smartcontractkit/libocr/quorumhelper"
@@ -16,6 +17,17 @@ import (
 	"github.com/smartcontractkit/libocr/offchainreporting2plus/ocr3types"
 )
 
+var (
+	// ballastAlloc is a byte slice initialized to 1GB to reduce CPU cycles spent in garbage collection.
+	// The plugin's data source pipeline performs many small allocations, which can frequently trigger the GC
+	// and increase CPU usage during the mark phase. The ballast allocation is virtually addressed and does not
+	// consume physical memory unless accessed. Since the Go GC runs when the heap size doubles, this ensures
+	// GC is only triggered when the heap grows to 2GB.
+	ballastAlloc []byte
+	ballastOnce  sync.Once
+	ballastSz    int = 1e9 // 1GB
+)
+
 // Additional limits so we can more effectively bound the size of observations
 // NOTE: These are hardcoded because these exact values are relied upon as a
 // property of coming to consensus, it's too dangerous to make these
@@ -261,6 +273,11 @@ func (f *PluginFactory) NewReportingPlugin(ctx context.Context, cfg ocr3types.Re
 		return nil, ocr3types.ReportingPluginInfo{}, fmt.Errorf("NewReportingPlugin failed to create observation codec: %w", err)
 	}
 
+	// Initialize the memory ballast
+	ballastOnce.Do(func() {
+		ballastAlloc = make([]byte, ballastSz)
+	})
+
 	return &Plugin{
 			f.Config,
 			onchainConfig.PredecessorConfigDigest,