chore: prevent profiler from being used with versions of node 10 with…

… GC pauses (#242)

* chore: prevent profiler from being used with versions of node 10 with GC bug

* Update and link to docs

* add tests for node semver limit

README.md

@@ -14,8 +14,21 @@ deprecation policy.*
 
 ## Prerequisites
 
-1. Your application will need to be using Node.js version 6.12.3 or greater, 
-or Node.js 8.9.4 or greater.
+1. Your application will need to be using Node.js version 6.12.3 or greater,
+Node.js 8.9.4 or greater, or Node.js 10.4.1 or greater. The profiler will not
+be enabled when using earlier versions of Node 6, 8, and 10 because the
+profiler is not stable with those versions of Node.js.
+    * Versions of Node.js 6 prior to 6.12.3 are impacted by
+    [this](https://bugs.chromium.org/p/v8/issues/detail?id=4959) issue, which can
+    cause segmentation faults when heap profiling is enabled.
+    * Versions of Node.js before Node.js 8 prior to 8.9.4 are impacted by
+    [this](https://bugs.chromium.org/p/v8/issues/detail?id=6623) issue, which
+    causes a memory leak when time profiling is enabled.
+    * Versions of Node.js 10 prior to 10.4.1 are impacted by
+    [this](https://bugs.chromium.org/p/chromium/issues/detail?id=847863) issue,
+    which can cause garbage collection to take several minutes when heap
+    profiling is enabled.
+
 1. You will need a project in the [Google Developers Console][cloud-console]. 
 Your application can run anywhere, but the profiler data is associated with a
 particular project.

package.json

@@ -82,6 +82,6 @@
     ]
   },
   "engines": {
-    "node": "6.12.3 - 7.0.0 || >=8.9.4"
+    "node": ">=6.12.3 <8.0.0 || >=8.9.4 <10.0.0 || >=10.4.1"
   }
 }

ts/src/index.ts

@@ -23,6 +23,7 @@ import * as path from 'path';
 import {normalize} from 'path';
 import * as pify from 'pify';
 import * as semver from 'semver';
+import {SemVer} from 'semver';
 
 import {Config, defaultConfig, ProfilerConfig} from './config';
 import {Profiler} from './profiler';
@@ -121,19 +122,32 @@ async function initConfigMetadata(config: ProfilerConfig):
   return config;
 }
 
+
+/**
+ * Returns true if the version passed in satifised version requirements
+ * specified in the profiler's package.json.
+ *
+ * Exported for testing.
+ */
+export function nodeVersionOkay(version: string|SemVer): boolean {
+  // Coerce version if possible, to remove any pre-release, alpha, beta, etc
+  // tags.
+  version = semver.coerce(version) || version;
+  return semver.satisfies(version, pjson.engines.node);
+}
+
 /**
  * Initializes the config, and starts heap profiler if the heap profiler is
  * needed. Returns a profiler if creation is successful. Otherwise, returns
  * rejected promise.
  */
 export async function createProfiler(config: Config): Promise<Profiler> {
-  // Coerce version if possible, to remove any pre-release, alpha, beta, etc
-  // tags.
-  const version = semver.coerce(process.version) || process.version;
-  if (!semver.satisfies(version, pjson.engines.node)) {
+  if (!nodeVersionOkay(process.version)) {
     throw new Error(
         `Could not start profiler: node version ${process.version}` +
-        ` does not satisfies "${pjson.engines.node}"`);
+        ` does not satisfies "${pjson.engines.node}"` +
+        '\nSee https://github.com/GoogleCloudPlatform/cloud-profiler-nodejs#prerequisites' +
+        ' for details.');
   }
 
   let profilerConfig: ProfilerConfig = initConfigLocal(config);

ts/test/test-init-config.ts

@@ -21,12 +21,51 @@ import * as extend from 'extend';
 import * as gcpMetadata from 'gcp-metadata';
 import * as sinon from 'sinon';
 
-import {createProfiler} from '../src/index';
+import {createProfiler, nodeVersionOkay} from '../src/index';
 import {Profiler} from '../src/profiler';
 import * as heapProfiler from '../src/profilers/heap-profiler';
 
 const v8HeapProfiler = require('bindings')('sampling_heap_profiler');
 
+describe('nodeVersionOkay', () => {
+  it('should accept alpha versions', () => {
+    assert.equal(true, nodeVersionOkay('v11.0.0-alpha.1'));
+  });
+  it('should accept beta versions', () => {
+    assert.equal(true, nodeVersionOkay('v8.9.10-beta.2'));
+  });
+  it('should accept nightly versions', () => {
+    assert.equal(true, nodeVersionOkay('v11.0.0-nightly2018000000'));
+  });
+  it('should accept pre-release versions', () => {
+    assert.equal(true, nodeVersionOkay('v11.0.0-pre'));
+  });
+  it('should accept v6.12.3', () => {
+    assert.equal(true, nodeVersionOkay('v6.12.3'));
+  });
+  it('should not accept v6.12.2', () => {
+    assert.equal(false, nodeVersionOkay('v6.12.2'));
+  });
+  it('should accept v8.9.4', () => {
+    assert.equal(true, nodeVersionOkay('v8.9.4'));
+  });
+  it('should not accept v8.9.3', () => {
+    assert.equal(false, nodeVersionOkay('v8.9.3'));
+  });
+  it('should accept v10.4.1', () => {
+    assert.equal(true, nodeVersionOkay('v10.4.1'));
+  });
+  it('should not accept v10.4.0', () => {
+    assert.equal(false, nodeVersionOkay('v10.4.0'));
+  });
+  it('should accept node 7', () => {
+    assert.equal(true, nodeVersionOkay('v7.7.7'));
+  });
+  it('should accept node 9', () => {
+    assert.equal(true, nodeVersionOkay('v9.9.9'));
+  });
+});
+
 describe('createProfiler', () => {
   let savedEnv: NodeJS.ProcessEnv;
   let metadataStub: sinon.SinonStub|undefined;