Multi-thread support for applyTemplate

lib/docx-pool.ts

@@ -0,0 +1,35 @@
+import Piscina from 'piscina';
+import path from 'node:path';
+import { availableParallelism } from 'node:os';
+
+const configuredThreads = Number(
+  process.env.DOCX_WORKERS || 4
+);
+
+const maxThreads = Math.max(
+  1,
+  Math.min(
+    Number.isFinite(configuredThreads) && configuredThreads > 0
+      ? Math.floor(configuredThreads)
+      : 4,
+    Math.max(1, availableParallelism() - 1)
+  )
+);
+
+const globalForDocx = globalThis as typeof globalThis & {
+  docxPool?: Piscina;
+};
+
+export const docxPool =
+  globalForDocx.docxPool ??=
+    new Piscina({
+      filename: path.resolve(
+        process.cwd(),
+        'workers/dist/docx.worker.mjs'
+      ),
+      minThreads: 1,
+      maxThreads,
+      idleTimeout: 30000,
+      maxQueue: 'auto',
+      concurrentTasksPerWorker: 1
+    });