Alternative approach to prevent long-log truncation: explicitly setti…

…ng process.stdout to blocking. See nodejs/node#6456 for a discussion of the issue and a version of the fix used here.

Signed-off-by: mrickard <mrickard@newrelic.com>

lib/collector/serverless.js

@@ -246,6 +246,8 @@ class ServerlessCollector {
     ]) + '\n'
 
     if (sync) {
+      const s = process.stdout
+      s._handle && s._handle.setBlocking && s._handle.setBlocking(true)
       fs.writeSync(process.stdout.fd, serializedPayload)
     } else {
       process.stdout.write(serializedPayload)

test/unit/collector/serverless.test.js

@@ -153,11 +153,12 @@ describe('ServerlessCollector API', () => {
   describe('#flushPayload', () => {
     let logStub = null
 
-    before(() => {
-      logStub = sinon.stub(process.stdout, 'write').callsFake(() => {})
+    beforeEach(() => {
+      logStub = sinon.stub(process.stdout, 'write').callsFake(() => {
+      })
     })
 
-    after(() => {
+    afterEach(() => {
       logStub.restore()
     })
 
@@ -172,5 +173,23 @@ describe('ServerlessCollector API', () => {
         done()
       })
     })
+    it('handles very large payload and writes formatted to stdout', done => {
+      api.payload = {type: 'test payload'}
+      for (let i = 0; i < 4096; i++) {
+        api.payload[`customMetric${i}`] = Math.floor(Math.random() * 100000)
+      }
+
+      api.flushPayload(() => {
+        const logPayload = JSON.parse(logStub.getCall(0).args[0])
+        const buf = Buffer.from(logPayload[2], 'base64')
+        zlib.gunzip(buf, (err, unpack) => {
+          expect(err).to.be.null
+          const payload = JSON.parse(unpack)
+          expect(payload.data).to.be.ok
+          expect(Object.keys(payload.data)).to.have.lengthOf.above(4000)
+          done()
+        })
+      })
+    })
   })
 })