From 25a20843b63f98c22782b2c735f54e93c3686525 Mon Sep 17 00:00:00 2001
From: kkHAIKE <kkhaike@gmail.com>
Date: Fri, 23 May 2025 10:35:28 +0800
Subject: [PATCH 1/6] Add mallocTrim command to vmTool

---
 arthas-vmtool/src/main/java/arthas/VmTool.java  |  6 ++++++
 .../src/main/java/arthas/VmToolMXBean.java      |  5 +++++
 .../src/main/native/src/jni-library.cpp         | 17 ++++++++++++++++-
 .../core/command/monitor200/VmToolCommand.java  |  7 ++++++-
 4 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/arthas-vmtool/src/main/java/arthas/VmTool.java b/arthas-vmtool/src/main/java/arthas/VmTool.java
index 19d2c6c0bf5..ff471c5113c 100644
--- a/arthas-vmtool/src/main/java/arthas/VmTool.java
+++ b/arthas-vmtool/src/main/java/arthas/VmTool.java
@@ -116,4 +116,10 @@ public Class<?>[] getAllLoadedClasses() {
         return getAllLoadedClasses0(Class.class);
     }
 
+    @Override
+    public boolean mallocTrim() {
+        return mallocTrim0();
+    }
+
+    private static synchronized native boolean mallocTrim0();
 }
diff --git a/arthas-vmtool/src/main/java/arthas/VmToolMXBean.java b/arthas-vmtool/src/main/java/arthas/VmToolMXBean.java
index 076a8f6977a..bdfb0f4077d 100644
--- a/arthas-vmtool/src/main/java/arthas/VmToolMXBean.java
+++ b/arthas-vmtool/src/main/java/arthas/VmToolMXBean.java
@@ -57,4 +57,9 @@ public interface VmToolMXBean {
      * 获取所有已加载的类
      */
     public Class<?>[] getAllLoadedClasses();
+
+    /**
+     * glibc 释放空闲内存
+     */
+    public boolean mallocTrim();
 }
diff --git a/arthas-vmtool/src/main/native/src/jni-library.cpp b/arthas-vmtool/src/main/native/src/jni-library.cpp
index dd11e2ef810..ebbfe05ebb3 100644
--- a/arthas-vmtool/src/main/native/src/jni-library.cpp
+++ b/arthas-vmtool/src/main/native/src/jni-library.cpp
@@ -4,6 +4,9 @@
 #include <jvmti.h>
 #include "arthas_VmTool.h" // under target/native/javah/
 
+#ifdef __GLIBC__
+#include <malloc.h>
+#endif
 
 static jvmtiEnv *jvmti;
 static jlong tagCounter = 0;
@@ -204,4 +207,16 @@ JNIEXPORT jobjectArray JNICALL Java_arthas_VmTool_getAllLoadedClasses0
     }
     jvmti->Deallocate(reinterpret_cast<unsigned char *>(classes));
     return array;
-}
\ No newline at end of file
+}
+
+
+extern "C"
+JNIEXPORT jboolean JNICALL Java_arthas_VmTool_mallocTrim
+        (JNIEnv *env, jclass thisClass) {
+#ifdef __GLIBC__
+    if (!::malloc_trim(0)) {
+        return JNI_FALSE;
+    }
+#endif
+    return JNI_TRUE;
+}
diff --git a/core/src/main/java/com/taobao/arthas/core/command/monitor200/VmToolCommand.java b/core/src/main/java/com/taobao/arthas/core/command/monitor200/VmToolCommand.java
index 548f66acfe6..a5a67ace093 100644
--- a/core/src/main/java/com/taobao/arthas/core/command/monitor200/VmToolCommand.java
+++ b/core/src/main/java/com/taobao/arthas/core/command/monitor200/VmToolCommand.java
@@ -157,7 +157,7 @@ public void setThreadId(int threadId) {
     }
 
     public enum VmToolAction {
-        getInstances, forceGc, interruptThread
+        getInstances, forceGc, interruptThread, mallocTrim
     }
 
     @Override
@@ -238,6 +238,11 @@ public void process(final CommandProcess process) {
                 process.write("\n");
                 process.end();
 
+                return;
+            } else if (VmToolAction.mallocTrim.equals(action)) {
+                boolean result = vmToolInstance().mallocTrim();
+                process.write("\n");
+                process.end(result ? 0 : -1, "mallocTrim result: " + result);
                 return;
             }
 

From c2b8b10b07ee10037824d3f6536918179f9bf4f3 Mon Sep 17 00:00:00 2001
From: kkHAIKE <kkhaike@gmail.com>
Date: Fri, 23 May 2025 10:40:13 +0800
Subject: [PATCH 2/6] remove empty line

---
 arthas-vmtool/src/main/native/src/jni-library.cpp | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arthas-vmtool/src/main/native/src/jni-library.cpp b/arthas-vmtool/src/main/native/src/jni-library.cpp
index ebbfe05ebb3..abc1421a7d8 100644
--- a/arthas-vmtool/src/main/native/src/jni-library.cpp
+++ b/arthas-vmtool/src/main/native/src/jni-library.cpp
@@ -209,7 +209,6 @@ JNIEXPORT jobjectArray JNICALL Java_arthas_VmTool_getAllLoadedClasses0
     return array;
 }
 
-
 extern "C"
 JNIEXPORT jboolean JNICALL Java_arthas_VmTool_mallocTrim
         (JNIEnv *env, jclass thisClass) {

From f65f5e5041f12df415e36ca3e407979e5bde8514 Mon Sep 17 00:00:00 2001
From: kkHAIKE <kkhaike@gmail.com>
Date: Fri, 23 May 2025 11:21:36 +0800
Subject: [PATCH 3/6] add EXAMPLE

---
 arthas-vmtool/src/main/native/src/jni-library.cpp               | 2 +-
 .../taobao/arthas/core/command/monitor200/VmToolCommand.java    | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/arthas-vmtool/src/main/native/src/jni-library.cpp b/arthas-vmtool/src/main/native/src/jni-library.cpp
index abc1421a7d8..3e9fdb2717b 100644
--- a/arthas-vmtool/src/main/native/src/jni-library.cpp
+++ b/arthas-vmtool/src/main/native/src/jni-library.cpp
@@ -210,7 +210,7 @@ JNIEXPORT jobjectArray JNICALL Java_arthas_VmTool_getAllLoadedClasses0
 }
 
 extern "C"
-JNIEXPORT jboolean JNICALL Java_arthas_VmTool_mallocTrim
+JNIEXPORT jboolean JNICALL Java_arthas_VmTool_mallocTrim0
         (JNIEnv *env, jclass thisClass) {
 #ifdef __GLIBC__
     if (!::malloc_trim(0)) {
diff --git a/core/src/main/java/com/taobao/arthas/core/command/monitor200/VmToolCommand.java b/core/src/main/java/com/taobao/arthas/core/command/monitor200/VmToolCommand.java
index a5a67ace093..024409f84c5 100644
--- a/core/src/main/java/com/taobao/arthas/core/command/monitor200/VmToolCommand.java
+++ b/core/src/main/java/com/taobao/arthas/core/command/monitor200/VmToolCommand.java
@@ -56,6 +56,7 @@
         + "  vmtool --action getInstances --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader --className org.springframework.context.ApplicationContext\n"
         + "  vmtool --action forceGc\n"
         + "  vmtool --action interruptThread -t 1\n"
+        + "  vmtool --action mallocTrim\n"
         + Constants.WIKI + Constants.WIKI_HOME + "vmtool")
 //@formatter:on
 public class VmToolCommand extends AnnotatedCommand {

From 0da277913dab7aa2069ebfd5c180cbb1867a8949 Mon Sep 17 00:00:00 2001
From: kkHAIKE <kkhaike@gmail.com>
Date: Wed, 4 Jun 2025 08:59:06 +0800
Subject: [PATCH 4/6] Change return type to int

---
 arthas-vmtool/src/main/java/arthas/VmTool.java            | 4 ++--
 arthas-vmtool/src/main/java/arthas/VmToolMXBean.java      | 2 +-
 arthas-vmtool/src/main/native/src/jni-library.cpp         | 8 +++-----
 .../arthas/core/command/monitor200/VmToolCommand.java     | 5 +++--
 4 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/arthas-vmtool/src/main/java/arthas/VmTool.java b/arthas-vmtool/src/main/java/arthas/VmTool.java
index ff471c5113c..97e00d481e1 100644
--- a/arthas-vmtool/src/main/java/arthas/VmTool.java
+++ b/arthas-vmtool/src/main/java/arthas/VmTool.java
@@ -117,9 +117,9 @@ public Class<?>[] getAllLoadedClasses() {
     }
 
     @Override
-    public boolean mallocTrim() {
+    public int mallocTrim() {
         return mallocTrim0();
     }
 
-    private static synchronized native boolean mallocTrim0();
+    private static synchronized native int mallocTrim0();
 }
diff --git a/arthas-vmtool/src/main/java/arthas/VmToolMXBean.java b/arthas-vmtool/src/main/java/arthas/VmToolMXBean.java
index bdfb0f4077d..d178645e2c7 100644
--- a/arthas-vmtool/src/main/java/arthas/VmToolMXBean.java
+++ b/arthas-vmtool/src/main/java/arthas/VmToolMXBean.java
@@ -61,5 +61,5 @@ public interface VmToolMXBean {
     /**
      * glibc 释放空闲内存
      */
-    public boolean mallocTrim();
+    public int mallocTrim();
 }
diff --git a/arthas-vmtool/src/main/native/src/jni-library.cpp b/arthas-vmtool/src/main/native/src/jni-library.cpp
index 3e9fdb2717b..c363f878776 100644
--- a/arthas-vmtool/src/main/native/src/jni-library.cpp
+++ b/arthas-vmtool/src/main/native/src/jni-library.cpp
@@ -210,12 +210,10 @@ JNIEXPORT jobjectArray JNICALL Java_arthas_VmTool_getAllLoadedClasses0
 }
 
 extern "C"
-JNIEXPORT jboolean JNICALL Java_arthas_VmTool_mallocTrim0
+JNIEXPORT jint JNICALL Java_arthas_VmTool_mallocTrim0
         (JNIEnv *env, jclass thisClass) {
 #ifdef __GLIBC__
-    if (!::malloc_trim(0)) {
-        return JNI_FALSE;
-    }
+    return ::malloc_trim(0);
 #endif
-    return JNI_TRUE;
+    return -1;
 }
diff --git a/core/src/main/java/com/taobao/arthas/core/command/monitor200/VmToolCommand.java b/core/src/main/java/com/taobao/arthas/core/command/monitor200/VmToolCommand.java
index 024409f84c5..1e0d235ad3e 100644
--- a/core/src/main/java/com/taobao/arthas/core/command/monitor200/VmToolCommand.java
+++ b/core/src/main/java/com/taobao/arthas/core/command/monitor200/VmToolCommand.java
@@ -241,9 +241,10 @@ public void process(final CommandProcess process) {
 
                 return;
             } else if (VmToolAction.mallocTrim.equals(action)) {
-                boolean result = vmToolInstance().mallocTrim();
+                int result = vmToolInstance().mallocTrim();
                 process.write("\n");
-                process.end(result ? 0 : -1, "mallocTrim result: " + result);
+                process.end(result == 1 ? 0 : -1, "mallocTrim result: " +
+                    (result == 1 ? "true" : (result == 0 ? "false" : "not supported")));
                 return;
             }
 

From acd574a845f15cdc91c814f57bb9de6f60264824 Mon Sep 17 00:00:00 2001
From: kkHAIKE <kkhaike@gmail.com>
Date: Fri, 6 Jun 2025 16:27:10 +0800
Subject: [PATCH 5/6] add mallocStats and some test

---
 arthas-vmtool/src/main/java/arthas/VmTool.java       |  6 ++++++
 arthas-vmtool/src/main/java/arthas/VmToolMXBean.java |  5 +++++
 arthas-vmtool/src/main/native/src/jni-library.cpp    | 11 +++++++++++
 arthas-vmtool/src/test/java/arthas/VmToolTest.java   | 12 ++++++++++++
 .../core/command/monitor200/VmToolCommand.java       |  9 ++++++++-
 5 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/arthas-vmtool/src/main/java/arthas/VmTool.java b/arthas-vmtool/src/main/java/arthas/VmTool.java
index 97e00d481e1..96ca5380ee1 100644
--- a/arthas-vmtool/src/main/java/arthas/VmTool.java
+++ b/arthas-vmtool/src/main/java/arthas/VmTool.java
@@ -122,4 +122,10 @@ public int mallocTrim() {
     }
 
     private static synchronized native int mallocTrim0();
+
+    @Override
+    public boolean mallocStats() {
+        return mallocStats0();
+    }
+    private static synchronized native boolean mallocStats0();
 }
diff --git a/arthas-vmtool/src/main/java/arthas/VmToolMXBean.java b/arthas-vmtool/src/main/java/arthas/VmToolMXBean.java
index d178645e2c7..cbaf4aea5ac 100644
--- a/arthas-vmtool/src/main/java/arthas/VmToolMXBean.java
+++ b/arthas-vmtool/src/main/java/arthas/VmToolMXBean.java
@@ -62,4 +62,9 @@ public interface VmToolMXBean {
      * glibc 释放空闲内存
      */
     public int mallocTrim();
+
+    /**
+     * glibc 输出内存状态到应用的 stderr
+     */
+    public boolean mallocStats();
 }
diff --git a/arthas-vmtool/src/main/native/src/jni-library.cpp b/arthas-vmtool/src/main/native/src/jni-library.cpp
index c363f878776..69650e5e3f5 100644
--- a/arthas-vmtool/src/main/native/src/jni-library.cpp
+++ b/arthas-vmtool/src/main/native/src/jni-library.cpp
@@ -217,3 +217,14 @@ JNIEXPORT jint JNICALL Java_arthas_VmTool_mallocTrim0
 #endif
     return -1;
 }
+
+extern "C"
+JNIEXPORT jboolean JNICALL Java_arthas_VmTool_mallocStats0
+        (JNIEnv *env, jclass thisClass) {
+#ifdef __GLIBC__
+    ::malloc_stats();
+    return JNI_TRUE;
+#else
+    return JNI_FALSE;
+#endif
+}
diff --git a/arthas-vmtool/src/test/java/arthas/VmToolTest.java b/arthas-vmtool/src/test/java/arthas/VmToolTest.java
index b48e7607622..8e7126c5d0d 100644
--- a/arthas-vmtool/src/test/java/arthas/VmToolTest.java
+++ b/arthas-vmtool/src/test/java/arthas/VmToolTest.java
@@ -210,4 +210,16 @@ public void test_interrupt_thread() throws InterruptedException {
         TimeUnit.SECONDS.sleep(5);
         Assert.assertEquals(("interrupted " + interruptMe.getId() + " thread success."), re[0].getMessage());
     }
+
+    @Test
+    public void testMallocTrim() {
+        VmTool vmtool = initVmTool();
+        vmtool.mallocTrim();
+    }
+
+    @Test
+    public void testMallocStats() {
+        VmTool vmtool = initVmTool();
+        vmtool.mallocStats();
+    }
 }
diff --git a/core/src/main/java/com/taobao/arthas/core/command/monitor200/VmToolCommand.java b/core/src/main/java/com/taobao/arthas/core/command/monitor200/VmToolCommand.java
index 1e0d235ad3e..758b93323c1 100644
--- a/core/src/main/java/com/taobao/arthas/core/command/monitor200/VmToolCommand.java
+++ b/core/src/main/java/com/taobao/arthas/core/command/monitor200/VmToolCommand.java
@@ -57,6 +57,7 @@
         + "  vmtool --action forceGc\n"
         + "  vmtool --action interruptThread -t 1\n"
         + "  vmtool --action mallocTrim\n"
+        + "  vmtool --action mallocStats\n"
         + Constants.WIKI + Constants.WIKI_HOME + "vmtool")
 //@formatter:on
 public class VmToolCommand extends AnnotatedCommand {
@@ -158,7 +159,7 @@ public void setThreadId(int threadId) {
     }
 
     public enum VmToolAction {
-        getInstances, forceGc, interruptThread, mallocTrim
+        getInstances, forceGc, interruptThread, mallocTrim, mallocStats
     }
 
     @Override
@@ -246,6 +247,12 @@ public void process(final CommandProcess process) {
                 process.end(result == 1 ? 0 : -1, "mallocTrim result: " +
                     (result == 1 ? "true" : (result == 0 ? "false" : "not supported")));
                 return;
+            } else if (VmToolAction.mallocStats.equals(action)) {
+                boolean result = vmToolInstance().mallocStats();
+                process.write("\n");
+                process.end(result ? 0 : -1, "mallocStats result: " +
+                    (result ? "true" : "not supported"));
+                return;
             }
 
             process.end();

From c183b1dc0590fc6c653fb4c1e1948dc85b86cf47 Mon Sep 17 00:00:00 2001
From: kkHAIKE <kkhaike@gmail.com>
Date: Fri, 6 Jun 2025 16:41:30 +0800
Subject: [PATCH 6/6] add mallocTrim/mallocStats command doc

---
 site/docs/doc/vmtool.md    | 29 +++++++++++++++++++++++++++++
 site/docs/en/doc/vmtool.md | 29 +++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+)

diff --git a/site/docs/doc/vmtool.md b/site/docs/doc/vmtool.md
index a173b65691d..0620f0d1355 100644
--- a/site/docs/doc/vmtool.md
+++ b/site/docs/doc/vmtool.md
@@ -97,3 +97,32 @@ thread id 通过`-t`参数指定，可以使用 `thread`命令获取。
 ```bash
 vmtool --action interruptThread -t 1
 ```
+
+## glibc 释放空闲内存
+
+Linux man page: [malloc_trim](https://man7.org/linux/man-pages/man3/malloc_trim.3.html)
+
+```bash
+vmtool --action mallocTrim
+```
+
+## glibc 内存状态
+
+内存状态将会输出到应用的 stderr。Linux man page: [malloc_stats](https://man7.org/linux/man-pages/man3/malloc_stats.3.html)
+
+```bash
+vmtool --action mallocStats
+```
+
+输出到 stderr 的内容如下：
+
+```
+Arena 0:
+system bytes     =     135168
+in use bytes     =      74352
+Total (incl. mmap):
+system bytes     =     135168
+in use bytes     =      74352
+max mmap regions =          0
+max mmap bytes   =          0
+```
diff --git a/site/docs/en/doc/vmtool.md b/site/docs/en/doc/vmtool.md
index 6bd2f9a8151..e90652f0511 100644
--- a/site/docs/en/doc/vmtool.md
+++ b/site/docs/en/doc/vmtool.md
@@ -97,3 +97,32 @@ The thread id is specified by the `-t` parameter. It can be obtained using the `
 ```bash
 vmtool --action interruptThread -t 1
 ```
+
+## glibc Release Free Memory
+
+Linux man page: [malloc_trim](https://man7.org/linux/man-pages/man3/malloc_trim.3.html)
+
+```bash
+vmtool --action mallocTrim
+```
+
+## glibc Memory Status
+
+The memory status will be output to the application's stderr. Linux man page: [malloc_stats](https://man7.org/linux/man-pages/man3/malloc_stats.3.html)
+
+```bash
+vmtool --action mallocStats
+```
+
+The output to stderr is as follows:
+
+```
+Arena 0:
+system bytes     =     135168
+in use bytes     =      74352
+Total (incl. mmap):
+system bytes     =     135168
+in use bytes     =      74352
+max mmap regions =          0
+max mmap bytes   =          0
+```