context lost when tracing mongodb?

i focked this repo at https://github.com/hafeyang/zipkin-js/tree/master/packages/zipkin-instrumentation-mongodb

    ctxImpl.letContext(ctx, () => {
      const url = 'mongodb://localhost:27017/zipkin_test';
      MongoClient.connect(url, function(err, db) {
        const col = db.collection('somecollection');
        ctxImpl.letContext(ctx, () => {
          col.deleteMany({}, {}, function() {
            ctxImpl.letContext(ctx, () => {
              col.insertMany([{a: 1}, {a: 2}, {a: 3}], function() {
                db.close();
                const annotations = record.args.map(args => args[0]);
                annotations.forEach(a => console.log(a.traceId.traceId+" "+a.traceId.spanId+" "+a.traceId.parentId));
                console.log(annotations);
                done();
              });
            });
          });
        });
      });
    });

here is my test code , annotations logged and i found traceId changed,and i got 2 traceId.

may caused by context losing

detailed err description and code pls check https://github.com/hafeyang/zipkin-js/tree/master/packages/zipkin-instrumentation-mongodb

Thanks!

[codefromthecrypt]

keep open for now as I have another topic we need to resolve which is explicit use of contexts inside instrumentation (ex tracer.record(id, annotation)) which can help guarantee less loss of events.

[jcchavezs]

Worth to revisit this @adriancole ?