RN 29 packager: slow reloads

[pesterhazy]

With https://github.com/pesterhazy/boot-react-native/tree/develop, SimpleExampleApp reloading works again. However, if I make a change and then use Cmd+R in the simulator to reload completely, it take 30 seconds or more. This used work in <5 seconds.

Some observations:

• on Cmd-R, the app requests the bundle: localhost:8081/index.ios.bundle?platform=ios&dev=true&hot=false
• the packager scans all dependencies again. If I understand it correctly, it should only re-scan the files that have changed. So it considers the files changed.
• you can use DEBUG='ReactNativePackager:*' boot dev -pios to get more debug output from the packager. It's painfully slow; on first startup it take up to 60 seconds on my laptop to build its dependency tree
• presumably boot changes (the timestamps of?) more files than necessary, causing the packager to re-scan a lot

[pesterhazy]

When run using boot -v dev, boot reports that it links out a few files, ones that have actually, and touch a few others. Is there a way to make boot not touch the files that haven't changed?

Writing target dir(s)...
Filesystem: touching node_modules/goog.net.XhrIo.ResponseType.js...
Filesystem: touching node_modules/goog.net.WebSocket.js...
Filesystem: touching node_modules/goog.string.TypedString.js...
Filesystem: touching node_modules/goog.net.xpc.TransportTypes.js...
Filesystem: linking node_modules/mattsum.boot_react_native.shim_repl_print.js...
Filesystem: touching node_modules/goog.math.Size.js...
Filesystem: touching node_modules/goog.net.xpc.IframePollingTransport.Sender.js...
Filesystem: touching node_modules/goog.dom.safe.InsertAdjacentHtmlPosition.js...
Filesystem: linking node_modules/mattsum.simple_example.core.js...
Filesystem: touching node_modules/goog.log.Logger.js...
Filesystem: touching node_modules/goog.async.FreeList.js...
Filesystem: touching node_modules/goog.async.Delay.js...
Filesystem: touching node_modules/cljsjs.react.dom.js...
Filesystem: touching node_modules/goog.net.XmlHttp.ReadyState.js...
Filesystem: touching node_modules/goog.html.uncheckedconversions.js...
Filesystem: touching node_modules/goog.userAgent.js...
Filesystem: linking main.out/mattsum/boot_react_native/shim_boot_reload.js...
Filesystem: touching node_modules/goog.messaging.AbstractChannel.js...
Filesystem: touching main.out/goog/deps.js...
Filesystem: touching node_modules/goog.events.EventId.js...
Filesystem: touching node_modules/goog.messaging.MessageChannel.js...
Filesystem: linking node_modules/mattsum.boot_react_native.shim_boot_reload.js...
Filesystem: touching node_modules/goog.net.XhrLike.js...
Filesystem: touching node_modules/goog.net.WrapperXmlHttpFactory.js...
Filesystem: touching node_modules/goog.events.ListenableType.js...
Filesystem: touching node_modules/goog.net.xpc.js...
Filesystem: touching node_modules/goog.log.js...
Filesystem: touching main.out/mattsum/boot_react_native/shim_browser_repl_bootstrap.cljs...
Filesystem: linking main.out/adzerk/boot_reload.cljs.cache.edn...
Filesystem: touching node_modules/goog.Disposable.js...
Filesystem: touching node_modules/goog.events.EventType.js...
Filesystem: touching node_modules/reagent.dom.js...
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Filesystem: touching node_modules/goog.net.xpc.FrameElementMethodTransport.js...
Filesystem: touching node_modules/goog.html.SafeHtml.js...
Filesystem: touching main.js...
Filesystem: linking main.out/mattsum/boot_react_native/shim_repl_print.js...
Filesystem: touching node_modules/goog.events.EventLike.js...
Filesystem: touching node_modules/goog.html.TrustedResourceUrl.js...
Filesystem: touching node_modules/reagent.impl.component.js...
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Filesystem: touching node_modules/goog.Uri.js...
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Filesystem: touching dist.cljs.edn...
Filesystem: touching node_modules/goog.net.DefaultXmlHttpFactory.js...
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Filesystem: touching main.out/mattsum/boot_react_native/shim_boot_reload.cljs...
Filesystem: touching node_modules/mattsum.boot_react_native.shim_browser_repl_bootstrap.js.map...
Filesystem: touching node_modules/cljs.core.js...
Filesystem: touching node_modules/goog.net.EventType.js...
Filesystem: touching node_modules/adzerk.boot_reload.connection.js...
Filesystem: touching node_modules/cljs.pprint.js...
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Filesystem: touching node_modules/mattsum.boot_react_native.shim_repl_print.js.map...
Filesystem: touching node_modules/goog.dom.BrowserFeature.js...
Filesystem: touching node_modules/goog.html.SafeStyle.js...
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Filesystem: touching node_modules/goog.net.xpc.NativeMessagingTransport.js...
Filesystem: touching node_modules/adzerk.boot_reload.client.js...
Filesystem: touching main.out/goog/net/jsloader.js...
Filesystem: touching node_modules/goog.promise.Resolver.js...
Filesystem: touching node_modules/goog.Delay.js...
Filesystem: touching node_modules/goog.iter.js...
Filesystem: linking node_modules/mattsum.simple_example.core.js.map...
Filesystem: touching node_modules/goog.events.ListenerMap.js...
Filesystem: touching node_modules/goog.net.xpc.CrossPageChannelRole.js...
Filesystem: touching node_modules/goog.events.CaptureSimulationMode.js...
Filesystem: touching node_modules/cljs.reader.js...
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Filesystem: touching node_modules/adzerk.boot_reload.display.js...
Filesystem: touching node_modules/goog.net.WebSocket.MessageEvent.js...
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Filesystem: touching main.out/mattsum/boot_react_native/shim_boot_reload.cljs.cache.edn...
Filesystem: touching node_modules/goog.math.js...
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Filesystem: touching node_modules/cljs.repl.js...
Filesystem: touching node_modules/goog.net.xpc.ChannelStates.js...
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Filesystem: touching node_modules/clojure.browser.repl.js...
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Filesystem: touching node_modules/goog.net.WebSocket.EventType.js...
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Filesystem: touching node_modules/goog.disposable.IDisposable.js...
Filesystem: touching node_modules/goog.labs.userAgent.util.js...
Filesystem: linking main.out/mattsum/simple_example/core.js...
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Filesystem: touching node_modules/goog.array.js...
Filesystem: touching node_modules/goog.net.xpc.IframePollingTransport.Receiver.js...
Filesystem: linking main.out/mattsum/boot_react_native/shim_repl_print.cljs.cache.edn...
Filesystem: touching node_modules/clojure.browser.event.js...
Filesystem: touching node_modules/goog.net.xpc.Transport.js...
Filesystem: linking main.out/mattsum/simple_example/core.js.map...
Filesystem: touching node_modules/goog.async.Deferred.AlreadyCalledError.js...
Filesystem: touching node_modules/mattsum.boot_react_native.shim_boot_reload.cljs...
Filesystem: touching node_modules/mattsum.boot_react_native.shim_boot_reload.js.map...
Filesystem: touching node_modules/goog.object.js...
Filesystem: touching node_modules/adzerk.boot_reload.websocket.js...
Filesystem: touching node_modules/goog.debug.LogBuffer.js...
Filesystem: touching node_modules/goog.html.SafeStyleSheet.js...
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Filesystem: touching node_modules/goog.uri.utils.js...
Filesystem: touching node_modules/goog.net.xpc.CrossPageChannel.js...
Filesystem: touching node_modules/reagent.debug.js...
Filesystem: touching node_modules/goog.dom.TagName.js...
Filesystem: touching node_modules/goog.net.ErrorCode.js...
Filesystem: touching main.out/adzerk/boot_reload.js.map...
Filesystem: touching node_modules/goog.debug.LogManager.js...
Filesystem: touching node_modules/goog.net.jsloader.Error.js...
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Filesystem: touching main.out/boot/cljs/main26911.js...
Filesystem: touching node_modules/goog.debug.js...
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Filesystem: touching node_modules/goog.log.Level.js...
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Filesystem: touching main.out/mattsum/boot_react_native/shim_repl_print.js.map...
Filesystem: touching node_modules/goog.userAgent.product.js...
Filesystem: touching node_modules/goog.dom.DomHelper.js...
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Filesystem: touching node_modules/goog.net.xpc.DirectTransport.js...
Filesystem: touching node_modules/mattsum.boot_react_native.shim_browser_repl_bootstrap.js...
Filesystem: touching node_modules/goog.html.SafeScript.js...
Filesystem: touching node_modules/goog.json.Reviver.js...
Filesystem: touching main.out/boot/cljs/main26911.cljs.cache.edn...
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Filesystem: touching node_modules/goog.debug.Logger.js...
Filesystem: touching node_modules/clojure.set.js...
Filesystem: touching main.out/mattsum/boot_react_native/shim_browser_repl_bootstrap.js...
Filesystem: touching node_modules/boot.cljs.main26911.js.map...
Filesystem: touching node_modules/goog.async.WorkQueue.js...
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Filesystem: touching node_modules/reagent.impl.batching.js...
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Filesystem: touching main.out/mattsum/boot_react_native/shim_browser_repl_bootstrap.js.map...
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Filesystem: touching main.out/boot/cljs/main26911.js.map...
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Filesystem: touching node_modules/reagent.ratom.js...
Filesystem: touching node_modules/goog.events.Key.js...
Filesystem: touching node_modules/goog.events.BrowserEvent.js...
Filesystem: touching node_modules/adzerk.boot_reload.reload.js...
Filesystem: touching node_modules/goog.uri.utils.ComponentIndex.js...

[pesterhazy]

It looks like boot touches the target files if the input file's mtime changes, so we should look into why that happens.

[pesterhazy]

$ stat -f 'created="%SB" modified="%Sm" hardlinks="%l"' app/build/node_modules/reagent.ratom.js
created="Jul 29 11:56:27 2016" modified="Jul 29 11:56:27 2016" hardlinks="3"

# touch a single clojurescript file (not reagent.ratom.cljs)
# and wait for boot-cljs to recompile the file

$ bump
$ stat -f 'created="%SB" modified="%Sm" hardlinks="%l"' app/build/node_modules/reagent.ratom.js
created="Jul 29 11:56:27 2016" modified="Jul 29 12:14:57 2016" hardlinks="2"

The issue is that the file's mtime updated even though it didn't actually change; this, in turn, makes the RN packager discard the work it did in the previous run.

[pesterhazy]

Here's a log file of boot -v dev which shows how the files gets updated. Search for "reagent.ratom.js": https://gist.github.com/pesterhazy/56db04810cacd89660626bc6ce596297

Note that at the end it says touching node_modules/reagent.ratom.js

[pesterhazy]

Ok so this is fixed/worked around with https://github.com/pesterhazy/boot-react-native/commit/ecb8c89b6e470f1feefad099057a4d14f1b58e2f (although this also disables sourcemaps for now)

[pesterhazy]

Fixed in master. It's still not as fast as it could be (70s for initial packaging step), but most of this is cached.