Settings for heap dumps creation (#304)

src/main/kotlin/io/emeraldpay/dshackle/HeapDumpCreator.kt

@@ -0,0 +1,82 @@
+package io.emeraldpay.dshackle
+
+import com.sun.management.HotSpotDiagnosticMXBean
+import org.slf4j.LoggerFactory
+import org.springframework.util.ResourceUtils
+import java.io.File
+import java.io.FileNotFoundException
+import java.lang.management.ManagementFactory
+import java.nio.file.Files
+import java.nio.file.Paths
+import java.nio.file.attribute.BasicFileAttributes
+import java.text.SimpleDateFormat
+import java.util.Date
+import java.util.concurrent.Executors
+import java.util.concurrent.TimeUnit
+
+class HeapDumpCreator {
+    companion object {
+        private const val MAX_DUMPS = 3
+
+        private val log = LoggerFactory.getLogger(HeapDumpCreator::class.java)
+        private val executorService = Executors.newSingleThreadScheduledExecutor()
+
+        fun init() {
+            val envVars = System.getenv()
+            val enableCreateDumps = envVars["HEAP_DUMP_ENABLE"]?.toBoolean() ?: true
+            val dumpsPath = envVars["HEAP_DUMP_PATH"] ?: "/etc/dshackle/dumps"
+            val dumpsPathExists = heapDumpsPathExists(dumpsPath)
+                .also {
+                    if (!it) {
+                        log.warn("$dumpsPath does not exist")
+                    }
+                }
+
+            if (enableCreateDumps && dumpsPathExists) {
+                executorService.scheduleAtFixedRate({ dumpCheckTask(dumpsPath) }, 0, 30, TimeUnit.MINUTES)
+
+                configHeapDump(dumpsPath)
+            } else {
+                log.warn("Heap dump creation is turned off")
+            }
+        }
+
+        private fun configHeapDump(dumpsPath: String) {
+            val date = SimpleDateFormat("yyyyMMddHHmmss").format(Date())
+            val fileName = "$dumpsPath/heap_$date.hprof"
+
+            val bean = ManagementFactory.newPlatformMXBeanProxy(
+                ManagementFactory.getPlatformMBeanServer(),
+                "com.sun.management:type=HotSpotDiagnostic",
+                HotSpotDiagnosticMXBean::class.java
+            )
+            bean.setVMOption("HeapDumpOnOutOfMemoryError", "true")
+            bean.setVMOption("HeapDumpPath", fileName)
+        }
+
+        private fun heapDumpsPathExists(dumpsPath: String): Boolean {
+            return try {
+                ResourceUtils.getFile(dumpsPath).exists()
+            } catch (e: FileNotFoundException) {
+                false
+            }
+        }
+
+        private fun dumpCheckTask(dumpsPath: String) {
+            val files = File(dumpsPath).listFiles()
+                ?.filter { it.name.endsWith("hprof") }
+                ?: emptyList()
+
+            if (files.isNotEmpty()) {
+                log.warn("There are some heap dumps, please send them to dshackle developers")
+            }
+            if (files.size >= MAX_DUMPS) {
+                files.minBy {
+                    Files.readAttributes(Paths.get(it.absolutePath), BasicFileAttributes::class.java).creationTime()
+                }.run {
+                    this.delete()
+                }
+            }
+        }
+    }
+}

src/main/kotlin/io/emeraldpay/dshackle/Starter.kt

@@ -35,6 +35,8 @@ fun main(args: Array<String>) {
 
     Schedulers.enableMetrics()
 
+    HeapDumpCreator.init()
+
     val maxMemory: Long = Runtime.getRuntime().maxMemory() / (1024 * 1024).toLong()
     log.info("Max heap size: {} MB", maxMemory)