fix: switch to BatchSpanProcessor and flush spans when thread exits

src/controllers/opentelemetry.ts

@@ -1,5 +1,5 @@
 import { NodeSDK } from "@opentelemetry/sdk-node";
-import { SimpleSpanProcessor } from "@opentelemetry/sdk-trace-node";
+import { BatchSpanProcessor } from "@opentelemetry/sdk-trace-node";
 import { HttpInstrumentation } from "@opentelemetry/instrumentation-http";
 import { Resource } from "@opentelemetry/resources";
 import Debug from "debug";
@@ -10,9 +10,11 @@ import { ATTR_SERVICE_NAME } from '@opentelemetry/semantic-conventions';
 const jaegerHost = process.env.JAEGER_HOST ?? 'jaeger-otel-collector.sri';
 const jaegerPort = process.env.JAEGER_PORT ?? 4318;
 const jaegerResName = process.env.JAEGER_RES_NAME ?? '/v1/traces';
+
 const traceExporter = new OTLPTraceExporter({
   url: `http://${jaegerHost}:${jaegerPort}${jaegerResName}`
 });
+const spanProcessor = new BatchSpanProcessor(traceExporter);
 
 debug("Initializing Opentelemetry instrumentation...");
 const sdk = new NodeSDK({
@@ -22,10 +24,15 @@ const sdk = new NodeSDK({
   resource: new Resource({
     [ATTR_SERVICE_NAME]: "biothings-explorer",
   }),
-  // use simple span processor to avoid losing data when the forked process exits (taskHandler)
-  // @ts-ignore - fix from MetinSeylan/Nestjs-OpenTelemetry#63
-  spanProcessors: [new SimpleSpanProcessor(traceExporter)],
+  // @ts-ignore because MetinSeylan/Nestjs-OpenTelemetry#63
+  spanProcessors: [spanProcessor],
 });
 debug(`OTel URL http://${jaegerHost}:${jaegerPort}${jaegerResName}`);
 sdk.start();
 debug("Opentelemetry instrumentation initialized.");
+
+export async function flushRemainingSpans(): Promise<void> {
+  // avoid losing any spans in the buffer when taskHandler exits
+  debug("Flushing remaining spans...");
+  await spanProcessor.forceFlush();
+}

src/controllers/threading/taskHandler.ts

@@ -17,6 +17,7 @@ import { ProfilingIntegration } from "@sentry/profiling-node";
 import { Span, trace, context, propagation, Context, Tracer } from "@opentelemetry/api";
 import { Telemetry } from "@biothings-explorer/utils";
 import { InnerTaskData } from "@biothings-explorer/types";
+import { flushRemainingSpans } from "../opentelemetry";
 
 // use SENTRY_DSN environment variable
 try {
@@ -113,6 +114,7 @@ async function runTask({
     transaction.finish();
     span.end();
     Telemetry.removeOtelSpan();
+    await flushRemainingSpans();
   } catch (error) {
     debug("Sentry/OpenTelemetry transaction finish error. This does not affect execution.");
     debug(error);