[jb] add JB_MEM_PROFILE env var to capture heap usage

Author: akosyakov

components/ide/jetbrains/backend-plugin/src/main/kotlin/io/gitpod/jetbrains/remote/GitpodManager.kt

@@ -19,6 +19,7 @@ import git4idea.config.GitVcsApplicationSettings
 import io.gitpod.gitpodprotocol.api.GitpodClient
 import io.gitpod.gitpodprotocol.api.GitpodServerLauncher
 import io.gitpod.jetbrains.remote.services.HeartbeatService
+import io.gitpod.jetbrains.remote.utils.LatencyRecord
 import io.gitpod.jetbrains.remote.utils.Retrier.retry
 import io.gitpod.supervisor.api.*
 import io.gitpod.supervisor.api.Info.WorkspaceInfoResponse
@@ -38,11 +39,14 @@ import java.net.URI
 import java.net.http.HttpClient
 import java.net.http.HttpRequest
 import java.net.http.HttpResponse
+import java.nio.file.Files
+import java.nio.file.Paths
 import java.time.Duration
 import java.util.concurrent.CancellationException
 import java.util.concurrent.CompletableFuture
 import javax.websocket.DeploymentException
 
+
 @Service
 class GitpodManager : Disposable {
 
@@ -59,6 +63,35 @@ class GitpodManager : Disposable {
         lifetime.terminate()
     }
 
+    private val memProfileMode = System.getenv("JB_MEM_PROFILE").toBoolean()
+
+    init {
+        val memProfileJob = GlobalScope.launch {
+            if (application.isHeadlessEnvironment || !memProfileMode) {
+                return@launch
+            }
+            Files.newBufferedWriter(Paths.get("/tmp/jb_mem_profile.log")).use { writer ->
+                writer.write("")
+                writer.flush()
+                val allocatedRecord = LatencyRecord()
+                val usedRecord = LatencyRecord()
+                while (isActive) {
+                    val totalMemory = Runtime.getRuntime().totalMemory() / (1024 * 1024)
+                    val usedMemory = (Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory()) / (1024 * 1024)
+                    allocatedRecord.update(totalMemory)
+                    usedRecord.update(usedMemory)
+                    writer.write("allocated - current ${totalMemory}M, avg ${allocatedRecord.averageLatency}M, max ${allocatedRecord.maxLatency}M, 90% percentile ${allocatedRecord.percentile(
+                            90)}M\n")
+                    writer.write("used - current ${usedMemory}M,avg ${usedRecord.averageLatency}M, max ${usedRecord.maxLatency}M, 90% percentile ${usedRecord.percentile(
+                            90)}M\n")
+                    writer.flush()
+                    delay(1000)
+                }
+            }
+        }
+        lifetime.onTerminationOrNow { memProfileJob.cancel() }
+    }
+
     init {
         GlobalScope.launch {
             if (application.isHeadlessEnvironment) {
@@ -269,4 +302,4 @@ class GitpodManager : Disposable {
             serverJob.cancel()
         }
     }
-}
+}

components/ide/jetbrains/backend-plugin/src/main/kotlin/io/gitpod/jetbrains/remote/utils/LatencyRecord.kt

@@ -0,0 +1,35 @@
+// Copyright (c) 2022 Gitpod GmbH. All rights reserved.
+// Licensed under the GNU Affero General Public License (AGPL).
+// See License-AGPL.txt in the project root for license information.
+
+package io.gitpod.jetbrains.remote.utils
+
+import it.unimi.dsi.fastutil.longs.LongArrayList
+
+class LatencyRecord {
+    var totalLatency: Long = 0L
+    var maxLatency: Long = 0
+    val samples = LongArrayList()
+    var samplesSorted = false
+
+    fun update(latencyInMS: Long) {
+        samplesSorted = false
+        samples.add(latencyInMS)
+        totalLatency += latencyInMS
+        if (latencyInMS > maxLatency) {
+            maxLatency = latencyInMS
+        }
+    }
+
+    val averageLatency: Long
+        get() = totalLatency / samples.size
+
+    fun percentile(n: Int): Long {
+        if (!samplesSorted) {
+            samples.sort()
+            samplesSorted = true
+        }
+        val index = (samples.size * n / 100).coerceAtMost(samples.size - 1)
+        return samples.getLong(index)
+    }
+}