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fix: Fix hung launcher on shutdown of Safari #38

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merged 2 commits into from
Apr 20, 2022
Merged

fix: Fix hung launcher on shutdown of Safari #38

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43be149
fix: Fix hung launcher on shutdown of Safari
joeyparrish Apr 19, 2022
b010b4f
Add constant for WebDriver startup delay
joeyparrish Apr 20, 2022
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33 changes: 28 additions & 5 deletions index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,12 @@ const {installWebDrivers} = require('webdriver-installer');
const DRIVER_CACHE = path.join(os.homedir(), '.webdriver-installer-cache');
fs.mkdirSync(DRIVER_CACHE, {recursive: true});

// Delay on startup to allow the WebDriver server to start.
const WEBDRIVER_STARTUP_DELAY_SECONDS = 2;

// If it takes longer than this to close our WebDriver session, give up.
const CLOSE_WEBDRIVER_SESSION_TIMEOUT_SECONDS = 5;
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let driversInstalledPromise = null;

// Map nodejs OS names to Selenium platform names.
Expand Down Expand Up @@ -91,7 +97,7 @@ const LocalWebDriverBase = function(baseBrowserDecorator, args, logger) {
});

this.on('start', async (url) => {
await new Promise((resolve) => setTimeout(resolve, 2000));
await delay(WEBDRIVER_STARTUP_DELAY_SECONDS);

this.browser.init(this.spec, (error) => {
if (error) {
Expand All @@ -116,9 +122,18 @@ const LocalWebDriverBase = function(baseBrowserDecorator, args, logger) {
await this.stopWebdriver_();
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Say, what's the difference between the kill and forceKill operations? They both just call stopWebdriver_.
Is kill called in such a way that we don't need to worry about them being nested, or about a forceKIll being nested inside a kill?

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kill() and forceKill() are part of the launcher API, but in my logs, I don't see kill() being called. In a purely external-process-based launcher, the base classes would send different POSIX signals to the subprocess for kill() and forceKill() if I recall correctly.

I initially thought forceKill() should never fail or be infinitely delayed, so I tried adding a timeout at the level of forceKill(). But that didn't solve the issue. In the end, I added the timeout to the WebDriver quit command, since that's the only thing that can fail or be delayed.

So after all the debugging and logging, I concluded that kill() and forceKill() can still effectively be the same, except for the state tracking part.

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I see. I was going to suggest moving the new logic for saving the operation as a promise into stopWebdriver_, instead of forceKill. But if kill isn't being called I guess it doesn't matter.

};

this.forceKillOperation_ = null;

this.forceKill = async () => {
// Don't nest force-kill operations. If forceKill() was already called,
// just return the same Promise again.
if (this.state == 'BEING_FORCE_KILLED') {
return this.forceKillOperation_;
}

this.state = 'BEING_FORCE_KILLED';
await this.stopWebdriver_();
this.forceKillOperation_ = this.stopWebdriver_();
await this.forceKillOperation_;
};

const originalStart = this.start;
Expand Down Expand Up @@ -173,17 +188,25 @@ const LocalWebDriverBase = function(baseBrowserDecorator, args, logger) {

this.stopWebdriver_ = async () => {
if (this.browser) {
await new Promise(resolve => this.browser.quit(resolve));
// If it takes too long to close the session, give up and move on.
await Promise.race([
delay(CLOSE_WEBDRIVER_SESSION_TIMEOUT_SECONDS),
new Promise(resolve => this.browser.quit(resolve)),
]);
}

// Now that the driver connection and browser are closed, emit the signal
// that shuts down the driver executable.
// Now that the driver connection and browser are closed (or have timed
// out), emit the signal that shuts down the driver executable.
await this.emitAsync('kill');

this.state = 'FINISHED';
};
}

async function delay(seconds) {
await new Promise((resolve) => setTimeout(resolve, seconds * 1000));
}

// Generate a subclass of LocalWebDriverBase and return it.
function generateSubclass(
browserName, launcherName, driverCommand, getDriverArgs,
Expand Down