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Remove concept of self-limiting workers, will use cloudwatch metrics collection to scale fleet instead of queue length

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This commit is contained in:
Ben Gotow 2016-06-23 12:02:57 -07:00
parent f7c647f7ba
commit 8e692982bb
1 changed files with 19 additions and 26 deletions
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41
packages/nylas-sync/sync-process-manager.js
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@ -22,6 +22,16 @@ that expires quickly if the sync process doesn't refresh it.
If it does not find the key, it moves all of the accounts in the list back to
the unclaimed key.
Sync processes only claim an account for a fixed period of time. This means that
an engineer can add new sync machines to the pool and the load across instances
will balance on it's own. It also means one bad instance will not permanently
disrupt sync for any accounts. (Eg: instance has faulty network connection.)
Sync processes periodically claim accounts when they can find them, regardless
of how busy they are. A separate API (`/routes/monitoring`) allows CloudWatch
to decide whether to spin up instances or take them offline based on CPU/RAM
utilization across the pool.
*/
class SyncProcessManager {
@ -73,6 +83,8 @@ class SyncProcessManager {
let unseenIds = [].concat(accountIds);
console.log("ProcessManager: Starting scan for accountIds in database that are not present in Redis.")
return Promise.each(client.keysAsync(`accounts:*`), (key) =>
client.lrangeAsync(key, 0, 20000).then((foundIds) => {
unseenIds = unseenIds.filter((a) => !foundIds.includes(`${a}`))
@ -117,33 +129,14 @@ class SyncProcessManager {
}
update() {
this.ensureCapacity().then(() => {
console.log(`ProcessManager: Voluntering to sync additional account.`)
console.log(`ProcessManager: Searching for an unclaimed account to sync.`)
this.acceptUnclaimedAccount().finally(() => {
if (this._exiting) {
return;
}
this.update();
});
})
.catch((err) => {
console.log(`ProcessManager: Decided not to sync additional account. ${err.message}`)
setTimeout(() => this.update(), 5000)
});
}
ensureCapacity() {
if (os.freemem() < 20 * 1024 * 1024) {
return Promise.reject(new Error(`<20MB RAM free (${os.freemem()} bytes)`));
}
const fiveMinuteLoadAvg = os.loadavg()[1];
if (fiveMinuteLoadAvg > CPU_COUNT * 0.9) {
return Promise.reject(new Error(`CPU load > 90% (${fiveMinuteLoadAvg} - ${CPU_COUNT} cores)`));
}
if (this._exiting) {
return Promise.reject(new Error('Process is exiting.'))
}
return Promise.resolve();
}
acceptUnclaimedAccount() {