Using the CLI

In addition to calling APIs to check the memory used by user-mode processes, you can run CLI commands to collect memory statistics, check for memory leaks, and check memory integrity.

--mwatch: initializes memory debugging, registers signals, and outputs memory debugging information through the serial port.
--mrecord <f_path>: initializes memory debugging, registers signals, and saves the memory debugging information to the f_path file. If the f_path file fails to be created, output the memory debugging information through the serial port.

If the process to debug does not exit, you can use the signal mechanism to obtain the corresponding information:

kill -35 <pid> # Check the thread-level heap memory usage.
kill -36 <pid> # Check for heap memory leaks.
kill -37 <pid> # Check whether the head node of the heap memory is complete.

Sample Code

The sample code constructs a memory problem and uses the command line to perform memory debugging.

#include <pthread.h>
#include <stdlib.h>
#include <stdio.h>

#define MALLOC_LEAK_SIZE  0x300

void func(void) {
    char *ptr = malloc(MALLOC_LEAK_SIZE);
    memset(ptr, '3', MALLOC_LEAK_SIZE);
}

int main()
{
    char *ptr = malloc(MALLOC_LEAK_SIZE);
    memset(ptr, '1', MALLOC_LEAK_SIZE);
    func();
    while (1);
}

Compilation

For details, see Calling APIs.

Running the mwatch Command

OHOS # ./mem_check --mwatch // Run the task command to obtain the mem_check process PID, which is 4.
OHOS # 
OHOS # kill -35 4 // Check heap memory statistics.
OHOS # 
==PID:4== Heap memory statistics(bytes):
    [Check point]:
        #00: <arm_signal_process+0x5c>[0x58dfc] -> /lib/libc.so

    [TID: 18, Used: 0x640]

==PID:4== Total heap: 0x640 byte(s), Peak: 0x640 byte(s)

OHOS # kill -36 4 // Check for heap memory leaks.
OHOS # 
==PID:4== Detected memory leak(s):
    [Check point]:
        #00: <check_leak+0x1c4>[0x2da4c] -> /lib/libc.so
        #01: <arm_signal_process+0x5c>[0x58dfc] -> /lib/libc.so

    [TID:18 Leak:0x320 byte(s)] Allocated from:
        #00: <main+0x14>[0x724] -> mem_check
        #01: <(null)+0x2555a9dc>[0x219dc] -> /lib/libc.so

    [TID:18 Leak:0x320 byte(s)] Allocated from:
        #00: <func+0x14>[0x6ec] -> mem_check
        #01: <main+0x30>[0x740] -> mem_check
        #02: <(null)+0x2555a9dc>[0x219dc] -> /lib/libc.so

==PID:4== SUMMARY: 0x640 byte(s) leaked in 2 allocation(s).

OHOS # kill -37 4 // Check the integrity of the head node of the heap memory.
OHOS # 
Check heap integrity ok!

Call Stack Parsing

Save the debugging information to the test.txt file and use the script to parse the information to obtain the number of line where the memory leak occurs.

$ ./parse_mem_info.sh test.txt mem_check
Compiler is [gcc/llvm]: llvm
Now using addr2line ...

==PID:4== Detected memory leak(s):
    [Check point]:
        #00: <check_leak+0x1c4>[0x2da4c] -> /lib/libc.so
        #01: <arm_signal_process+0x5c>[0x58dfc] -> /lib/libc.so

    [TID:18 Leak:0x320 byte(s)] Allocated from:
        #00: <main+0x14>[0x724] at /usr1/xxx/TEST_ELF/mem_check.c:14
        #01: <(null)+0x2555a9dc>[0x219dc] -> /lib/libc.so

    [TID:18 Leak:0x320 byte(s)] Allocated from:
        #00: <func+0x14>[0x6ec] at /usr1/xxx/TEST_ELF/mem_check.c:8
        #01: <main+0x30>[0x740] at /usr1/xxx/TEST_ELF/mem_check.c:19
        #02: <(null)+0x2555a9dc>[0x219dc] -> /lib/libc.so

==PID:4== SUMMARY: 0x640 byte(s) leaked in 2 allocation(s).

Running the mrecord Command

1. Run the user program and specify the path of the file that stores the memory debugging information.

   OHOS # ./mem_check --mrecord /storage/check.txt
   

2. Run the kill -35 <pid> command to collect statistics on the memory information. The information is exported to a file. Run the cat command to view the information.

   OHOS # kill -35 4
   OHOS # Memory statistics information saved in /storage/pid(4)_check.txt
   
   OHOS # cat /storage/pid(4)_check.txt
   
   ==PID:4== Heap memory statistics(bytes):
       [Check point]:
           #00: <arm_signal_process+0x5c>[0x5973c] -> /lib/libc.so
   
       [TID: 18, Used: 0x640]
   
   ==PID:4== Total heap: 0x640 byte(s), Peak: 0x640 byte(s)
   

3. Run the kill -36 <pid> command to check memory integrity. The information is exported to a file. Run the cat command to view the information.

   OHOS # kill -36 4
   OHOS # Leak check information saved in /storage/pid(4)_check.txt
   
   OHOS # cat /storage/pid(4)_check.txt
   
   ==PID:4== Heap memory statistics(bytes):
       [Check point]:
           #00: <arm_signal_process+0x5c>[0x5973c] -> /lib/libc.so
   
       [TID: 18, Used: 0x640]
   
   ==PID:4== Total heap: 0x640 byte(s), Peak: 0x640 byte(s)
   
   ==PID:4== Detected memory leak(s):
       [Check point]:
           #00: <check_leak+0x1c4>[0x2e38c] -> /lib/libc.so
           #01: <arm_signal_process+0x5c>[0x5973c] -> /lib/libc.so
   
       [TID:18 Leak:0x320 byte(s)] Allocated from:
           #00: <main+0x14>[0x724] -> mem_check
           #01: <(null)+0x1fdd231c>[0x2231c] -> /lib/libc.so
   
       [TID:18 Leak:0x320 byte(s)] Allocated from:
           #00: <func+0x14>[0x6ec] -> mem_check
           #01: <main+0x30>[0x740] -> mem_check
           #02: <(null)+0x1fdd231c>[0x2231c] -> /lib/libc.so
   
   ==PID:4== SUMMARY: 0x640 byte(s) leaked in 2 allocation(s).
   

4. Run the kill -9 <pid> command to kill the current process. After the process exits, a memory integrity check is performed by default. The check result is output to a file. You can run the cat command to view it.

   OHOS # kill -9 4
   OHOS # Leak check information saved in /storage/pid(4)_check.txt
   
   Check heap integrity ok!
   
   OHOS # cat /storage/pid(4)_check.txt
   OHOS # 
   ==PID:4== Heap memory statistics(bytes):
       [Check point]:
           #00: <arm_signal_process+0x5c>[0x5973c] -> /lib/libc.so
   
       [TID: 18, Used: 0x640]
   
   ==PID:4== Total heap: 0x640 byte(s), Peak: 0x640 byte(s)
   
   ==PID:4== Detected memory leak(s):
       [Check point]:
           #00: <check_leak+0x1c4>[0x2e38c] -> /lib/libc.so
           #01: <arm_signal_process+0x5c>[0x5973c] -> /lib/libc.so
   
       [TID:18 Leak:0x320 byte(s)] Allocated from:
           #00: <main+0x14>[0x724] -> mem_check
           #01: <(null)+0x1fdd231c>[0x2231c] -> /lib/libc.so
   
       [TID:18 Leak:0x320 byte(s)] Allocated from:
           #00: <func+0x14>[0x6ec] -> mem_check
           #01: <main+0x30>[0x740] -> mem_check
           #02: <(null)+0x1fdd231c>[0x2231c] -> /lib/libc.so
   
   ==PID:4== SUMMARY: 0x640 byte(s) leaked in 2 allocation(s).
   
   ==PID:4== Detected memory leak(s):
       [Check point]:
           #00: <check_leak+0x1c4>[0x2e38c] -> /lib/libc.so
           #01: <exit+0x28>[0x11b2c] -> /lib/libc.so
   
       [TID:18 Leak:0x320 byte(s)] Allocated from:
           #00: <main+0x14>[0x724] -> mem_check
           #01: <(null)+0x1fdd231c>[0x2231c] -> /lib/libc.so
   
       [TID:18 Leak:0x320 byte(s)] Allocated from:
           #00: <func+0x14>[0x6ec] -> mem_check
           #01: <main+0x30>[0x740] -> mem_check
           #02: <(null)+0x1fdd231c>[0x2231c] -> /lib/libc.so
   
   ==PID:4== SUMMARY: 0x640 byte(s) leaked in 2 allocation(s).
   

NOTE
The preceding information recorded gradually is added to the file specified during initialization. Therefore, running the cat command can also display the historical information in the file.