Method executeCall

src/python/worker.ts:138–220

(functionName: string, args: unknown[])

  }

  private async executeCall(functionName: string, args: unknown[]): Promise<unknown> {
    let tempDirectory: string | undefined;

    try {
      tempDirectory = await createSecureTempDirectory('promptfoo-worker-');
      const requestFile = await writeSecureTempFile(
        tempDirectory,
        'request.json',
        safeJsonStringify(args) as string,
      );
      const responseFile = await writeSecureTempFile(tempDirectory, 'response.json', '');

      // Send CALL command with function name
      // Note: PythonShell.send() adds newline automatically in 'text' mode
      // Using pipe (|) delimiter to avoid conflicts with Windows drive letters (C:)
      const command = `CALL|${functionName}|${requestFile}|${responseFile}`;
      this.process!.send(command);

      // Wait for DONE
      await new Promise<unknown>((resolve, reject) => {
        this.pendingRequest = { responseFile, resolve, reject };
      });

      // Read response with exponential backoff retry.
      // Python verifies file readability before sending DONE, but OS-level delays may still occur.
      let responseData: string | undefined;
      let lastError: unknown;

      // Exponential backoff: 1ms, 2ms, 4ms, 8ms, 16ms, 32ms, 64ms, 128ms, 256ms, 512ms, 1024ms, 2048ms, 4096ms, 5000ms (capped)...
      // Total max wait: ~18 seconds (handles severe filesystem delays)
      for (let attempt = 0, delay = 1; attempt < 16; attempt++, delay = Math.min(delay * 2, 5000)) {
        try {
          responseData = await fs.readFile(responseFile, 'utf-8');
          if (attempt > 0) {
            logger.debug(`Response file read succeeded on attempt ${attempt + 1}`);
          }
          break;
        } catch (error: unknown) {
          lastError = error;
          if (error && typeof error === 'object' && 'code' in error && error.code === 'ENOENT') {
            // File doesn't exist yet, wait and retry with exponential backoff.
            await new Promise((resolve) => setTimeout(resolve, delay));
            continue;
          }
          // Non-ENOENT error, don't retry.
          throw error;
        }
      }

      // If we exhausted all retries, throw with debugging info
      if (!responseData) {
        try {
          const files = await fs.readdir(tempDirectory);
          logger.error(
            `Failed to read response file after 16 attempts (~18s). Expected: ${path.basename(responseFile)}, Found in temporary directory: ${files.join(', ')}`,
          );
        } catch {
          logger.error(