src: add trace events for env.cc #23674

jasnell · 2018-10-15T17:38:27Z

Adds a new node.environment trace event category that captures simple lifecycle events for an Environment:

This will be most useful for our own diagnostics around timers and such but it captures useful timing information for end users also.

Note: Will add test and docs in a bit

/cc @nodejs/diagnostics

Checklist

make -j4 test (UNIX), or vcbuild test (Windows) passes
tests and/or benchmarks are included
documentation is changed or added
commit message follows commit guidelines

nodejs-github-bot · 2018-10-15T17:38:29Z

@jasnell build started: https://ci.nodejs.org/blue/organizations/jenkins/node-test-pull-request-lite-pipeline/detail/node-test-pull-request-lite-pipeline/1252/pipeline

src/env.cc

addaleax · 2018-10-15T17:46:21Z

src/env.cc

+      TRACING_CATEGORY_NODE1(environment),
+      "Environment", this,
+      "args", std::move(traced_value));
+  }


Heads up … there’s a very good chance of the args/exec_args handling being moved to another method as part of better embedding support

Yeah, I was wondering about that. Hmm... perhaps we should make args have their own dedicated trace event category... or even make it part of the process __metadata so that it's always there if tracing is enabled. It's useful context either way.

@jasnell I think that depends… We’ve had a similar conversation in the node-report PR at #22712 – what arguments do we actually care about here? The ones passed on the original command line, to the Node.js CLI, or the one that this Node.js instance explicitly uses?

The distinction matters for embedder use cases; But maybe, as a more practical example: I’d like to add support for something similar to execArgv to Workers. I guess it makes sense to emit these per-Environment?

I'm thinking that the one that this Node.js instance explicitly uses... whichever are relevant to each specific Environment instance.

addaleax

Test also LGTM :)

src/env.cc

lundibundi · 2018-10-15T17:58:29Z

src/env.cc

+  TraceEventScope(const char* category,
+                  const char* name,
+                  void* id) : category_(category), name_(name), id_(id) {
+    TRACE_EVENT_NESTABLE_ASYNC_BEGIN0(category_, name_, id);


Perhaps also use member field id_?

lundibundi · 2018-10-15T18:02:04Z

test/parallel/test-trace-events-environment.js

+    fs.readFile(file, common.mustCall((err, data) => {
+      const traces = JSON.parse(data.toString()).traceEvents
+        .filter((trace) => trace.cat !== '__metadata');
+      traces.forEach((trace) => {


Any reason not to chain this and remove intermediate traces variable?

just consistency with the other trace event tests. We can simplify all of them in a single batch with a separate PR

Since there are some other changes to make in the test anyway, I'll just go ahead and simplify :-)

test/parallel/test-trace-events-environment.js

lundibundi · 2018-10-15T18:06:07Z

src/env.cc

@@ -231,6 +254,23 @@ void Environment::Start(const std::vector<std::string>& args,
  HandleScope handle_scope(isolate());
  Context::Scope context_scope(context());

+  if (*TRACE_EVENT_API_GET_CATEGORY_GROUP_ENABLED(
+      TRACING_CATEGORY_NODE1(environment))) {


Nit: != 0 for clarity? IIUC

@lundibundi I’m not sure, but quoting the V8 tracing header:

node/deps/v8/include/libplatform/v8-tracing.h

Line 228 in 561e30d

// The TRACE_EVENT macros should only use the value as a bool.

(I know this isn’t technically in a macro, but I think the recommendation from V8 makes sense in the same way?)

🤔 makes sense but we have

node/src/node_contextify.cc

Lines 661 to 662 in 561e30d

if (*TRACE_EVENT_API_GET_CATEGORY_GROUP_ENABLED(

TRACING_CATEGORY_NODE2(vm, script)) != 0) {

and

node/src/node_file.cc

Lines 92 to 93 in 561e30d

(*TRACE_EVENT_API_GET_CATEGORY_GROUP_ENABLED \

(TRACING_CATEGORY_NODE2(fs, sync)) != 0)

?

doesn't hurt to have the != 0 ... we can refactor them all out later if needed.

refack

Seems like a very useful feature.
Left some nits for the test

test/parallel/test-trace-events-environment.js

refack · 2018-10-15T18:10:36Z

test/parallel/test-trace-events-environment.js

+    const file = path.join(tmpdir.path, 'node_trace.1.log');
+
+    assert(fs.existsSync(file));
+    fs.readFile(file, common.mustCall((err, data) => {


For readability, if this is not significant to the tested code, could this be fs.readFileSync or await fs.promise.readfile

richardlau · 2018-10-15T18:16:34Z

test/parallel/test-trace-events-environment.js

+const tmpdir = require('../common/tmpdir');
+
+if (!common.isMainThread)
+  common.skip('process.chdir is not available in Workers');


Does that also apply to cwd for child_process.fork (as an alternative if it does not)?

It shouldn't, but that's a question for @addaleax and is a separate concern from this PR.

When using cwd, chdir() is executed in the child process, so, yes, I think this test could be written without process.chdir() and the need to skip it in Workers.

The chdir is there because of the generated trace event file. I'm inclined to leave the test as it is and refactor all of the trace event tests as a whole if this is the direction we want to go (they all follow this same pattern)

jasnell · 2018-10-15T22:47:09Z

CI: https://ci.nodejs.org/job/node-test-pull-request/17878/

refack

💯

jasnell · 2018-10-16T00:29:45Z

Resume: https://ci.nodejs.org/job/node-test-pull-request/17882/

lundibundi · 2018-10-16T06:42:48Z

test/parallel/test-trace-events-environment.js

+      });
+
+    let name;
+    while (name = names.shift())


Couldn't we have initial names as Set too and then use deepStrictEqual(checkSet, names) here?

jasnell · 2018-10-16T14:45:22Z

New CI: https://ci.nodejs.org/job/node-test-pull-request/17908/

jasnell · 2018-10-17T14:40:20Z

Resume CI: https://ci.nodejs.org/job/node-test-pull-request/17941/

PR-URL: nodejs#23674 Reviewed-By: Anna Henningsen <[email protected]> Reviewed-By: Denys Otrishko <[email protected]> Reviewed-By: Refael Ackermann <[email protected]> Reviewed-By: Ali Ijaz Sheikh <[email protected]> Reviewed-By: Matheus Marchini <[email protected]>

Trott · 2018-10-18T04:58:52Z

Landed in 72a48a2

Use the `cwd` option for `child_process` instead of `process.chdir()` to enable the trace events tests to run on workers. PR-URL: #23698 Refs: #23674 (comment) Reviewed-By: James M Snell <[email protected]> Reviewed-By: Colin Ihrig <[email protected]>

addaleax · 2018-10-20T06:12:06Z

Should this be backported to v10.x-staging? If yes please follow the guide and raise a backport PR, if not let me know or add the dont-land-on label.

PR-URL: #23674 Reviewed-By: Anna Henningsen <[email protected]> Reviewed-By: Denys Otrishko <[email protected]> Reviewed-By: Refael Ackermann <[email protected]> Reviewed-By: Ali Ijaz Sheikh <[email protected]> Reviewed-By: Matheus Marchini <[email protected]>

Use the `cwd` option for `child_process` instead of `process.chdir()` to enable the trace events tests to run on workers. PR-URL: #23698 Refs: #23674 (comment) Reviewed-By: James M Snell <[email protected]> Reviewed-By: Colin Ihrig <[email protected]>

Use the `cwd` option for `child_process` instead of `process.chdir()` to enable the trace events tests to run on workers. Backport-PR-URL: nodejs#23882 PR-URL: nodejs#23698 Refs: nodejs#23674 (comment) Reviewed-By: James M Snell <[email protected]> Reviewed-By: Colin Ihrig <[email protected]> Conflicts: test/parallel/test-trace-events-binding.js test/parallel/test-trace-events-category-used.js

Use the `cwd` option for `child_process` instead of `process.chdir()` to enable the trace events tests to run on workers. Conflicts: test/parallel/test-trace-events-binding.js test/parallel/test-trace-events-category-used.js Backport-PR-URL: #23882 PR-URL: #23698 Refs: #23674 (comment) Reviewed-By: James M Snell <[email protected]> Reviewed-By: Colin Ihrig <[email protected]>

src: add trace events for env.cc

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jasnell added lib / src Issues and PRs related to general changes in the lib or src directory. trace_events Issues and PRs related to V8, Node.js core, and userspace code trace events. labels Oct 15, 2018

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richardlau mentioned this pull request Oct 16, 2018

test: enable trace-events tests for workers #23698

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src: add trace events for env.cc #23674

src: add trace events for env.cc #23674

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	if (*TRACE_EVENT_API_GET_CATEGORY_GROUP_ENABLED(
	TRACING_CATEGORY_NODE2(vm, script)) != 0) {

	(*TRACE_EVENT_API_GET_CATEGORY_GROUP_ENABLED \
	(TRACING_CATEGORY_NODE2(fs, sync)) != 0)

src: add trace events for env.cc #23674

src: add trace events for env.cc #23674

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jasnell commented Oct 15, 2018

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