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8356870: HotSpotDiagnosticMXBean.dumpThreads and jcmd Thread.dump_to_file updates #25429

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8356870: HotSpotDiagnosticMXBean.dumpThreads and jcmd Thread.dump_to_file updates #25429

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586 changes: 418 additions & 168 deletions src/java.base/share/classes/jdk/internal/vm/ThreadDumper.java
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10 changes: 9 additions & 1 deletion src/jdk.management/share/classes/com/sun/management/HotSpotDiagnosticMXBean.java
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
/*
* Copyright (c) 2005, 2024, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2005, 2025, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
Expand Down Expand Up @@ -116,6 +116,13 @@ public interface HotSpotDiagnosticMXBean extends PlatformManagedObject {
* {@code outputFile} parameter must be an absolute path to a file that
* does not exist.
*
* <p> When the format is specified as {@link ThreadDumpFormat#JSON JSON}, the
* thread dump is generated in JavaScript Object Notation.
* <a href="doc-files/threadDump.schema.json">threadDump.schema.json</a>
* describes the thread dump format in draft
* <a href="https://tools.ietf.org/html/draft-json-schema-language-02">
* JSON Schema Language version 2</a>.
*
* <p> The thread dump will include output for all platform threads. It may
* include output for some or all virtual threads.
*
Expand Down Expand Up @@ -151,6 +158,7 @@ public static enum ThreadDumpFormat {
TEXT_PLAIN,
/**
* JSON (JavaScript Object Notation) format.
* @spec https://datatracker.ietf.org/doc/html/rfc8259 JavaScript Object Notation
*/
JSON,
}
Expand Down
175 changes: 175 additions & 0 deletions src/jdk.management/share/classes/com/sun/management/doc-files/threadDump.schema.json
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@@ -0,0 +1,175 @@
{
"type": "object",
"properties": {
"threadDump": {
"type": "object",
"properties": {
"processId": {
"type": "string",
"description": "The native process id of the Java virtual machine."
},
"time": {
"type": "string",
"description": "The time in ISO 8601 format when the thread dump was generated."
},
"runtimeVersion": {
"type": "string",
"description": "The runtime version, see java.lang.Runtime.Version"
},
"threadContainers": {
"type": "array",
"description": "The array of thread containers (thread groupings).",
"items": [
{
"type": "object",
"properties": {
"container": {
"type": "string",
"description": "The container name. The container name is unique."
},
"parent": {
"type": [
"string",
"null"
],
"description": "The parent container name or null for the root container."
},
"owner": {
"type": [
"string",
"null"
],
"description": "The thread identifier of the owner thread if owned."
},
"threads": {
"type": "array",
"description": "The array of threads in the thread container.",
"items": [
{
"type": "object",
"properties": {
"tid": {
"type": "string",
"description": "The thread identifier."
},
"time": {
"type": "string",
"description": "The time in ISO 8601 format that the thread was sampled."
},
"name": {
"type": "string",
"description": "The thread name."
},
"state": {
"type": "string",
"description": "The thread state (Thread::getState)."
},
"virtual" : {
"type": "boolean",
"description": "true for a virtual thread."
},
"parkBlocker": {
"type": [
"object"
],
"properties": {
"object": {
"type": "string",
"description": "The blocker object responsible for the thread parking."
},
"exclusiveOwnerThreadId": {
"type": "string",
"description": "The thread identifier of the owner when the blocker object has an owner."
}
},
"required": [
"object"
]
},
"blockedOn": {
"type": "string",
"description": "The object that the thread is blocked on waiting to enter/re-enter a synchronization block/method."
},
"waitingOn": {
"type": "string",
"description": "The object that the thread is waiting to be notified (Object.wait)."
},
"stack": {
"type": "array",
"description": "The thread stack. The first element is the top of the stack.",
"items": [
{
"type": "string",
"description": "A stack trace element (java.lang.StackTraceElement)."
}
]
},
"monitorsOwned": {
"type": "array",
"description": "The objects for which monitors are owned by the thread.",
"items": {
"type": "object",
"properties": {
"depth": {
"type": "integer",
"description": "The stack depth at which the monitors are owned."
},
"locks": {
"type": "array",
"items": {
"type": [
"string",
null
],
"description": "The object for which the monitor is owned by the thread, null if eliminated"
}
}
},
"required": [
"depth",
"locks"
]
}
},
"carrier": {
"type": "string",
"description": "The thread identifier of the carrier thread if mounted."
}
},
"required": [
"tid",
"time",
"name",
"state",
"stack"
]
}
]
},
"threadCount": {
"type": "string",
"description": "The number of threads in the thread container."
}
},
"required": [
"container",
"parent",
"owner",
"threads"
]
}
]
}
},
"required": [
"processId",
"time",
"runtimeVersion",
"threadContainers"
]
}
},
"required": [
"threadDump"
]
}
4 changes: 2 additions & 2 deletions src/jdk.management/share/classes/com/sun/management/internal/HotSpotDiagnostic.java
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
/*
* Copyright (c) 2005, 2024, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2005, 2025, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
Expand Down Expand Up @@ -153,7 +153,7 @@ public void dumpThreads(String outputFile, ThreadDumpFormat format) throws IOExc
throw new IllegalArgumentException("'outputFile' not absolute path");

try (OutputStream out = Files.newOutputStream(file, StandardOpenOption.CREATE_NEW)) {
dumpThreads(out, format);
dumpThreads(out, format);
}
}

Expand Down
27 changes: 23 additions & 4 deletions test/hotspot/jtreg/serviceability/dcmd/thread/ThreadDumpToFileTest.java
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
/*
* Copyright (c) 2021, 2023, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2021, 2025, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
Expand All @@ -25,6 +25,7 @@
* @test
* @bug 8284161 8287008
* @summary Basic test for jcmd Thread.dump_to_file
* @modules jdk.jcmd
* @library /test/lib
* @run junit/othervm ThreadDumpToFileTest
*/
Expand Down Expand Up @@ -66,7 +67,8 @@ void testPlainThreadDump() throws IOException {
@Test
void testJsonThreadDump() throws IOException {
Path file = genThreadDumpPath(".json");
jcmdThreadDumpToFile(file, "-format=json").shouldMatch("Created");
jcmdThreadDumpToFile(file, "-format=json")
.shouldMatch("Created");

// parse the JSON text
String jsonText = Files.readString(file);
Expand All @@ -89,7 +91,8 @@ void testDoNotOverwriteFile() throws IOException {
Path file = genThreadDumpPath(".txt");
Files.writeString(file, "xxx");

jcmdThreadDumpToFile(file, "").shouldMatch("exists");
jcmdThreadDumpToFile(file, "")
.shouldMatch("exists");

// file should not be overridden
assertEquals("xxx", Files.readString(file));
Expand All @@ -102,7 +105,23 @@ void testDoNotOverwriteFile() throws IOException {
void testOverwriteFile() throws IOException {
Path file = genThreadDumpPath(".txt");
Files.writeString(file, "xxx");
jcmdThreadDumpToFile(file, "-overwrite");
jcmdThreadDumpToFile(file, "-overwrite")
.shouldMatch("Created");
}

/**
* Test output file cannot be created.
*/
@Test
void testFileCreateFails() throws IOException {
Path badFile = Path.of(".").toAbsolutePath()
.resolve("does-not-exist")
.resolve("does-not-exist")
.resolve("threads.bad");
jcmdThreadDumpToFile(badFile, "-format=plain")
.shouldMatch("Failed");
jcmdThreadDumpToFile(badFile, "-format=json")
.shouldMatch("Failed");
}

/**
Expand Down
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