Ready for Review : 8042469 : Launcher changes for native memory tracking scalability enhancement (original) (raw)

Zhengyu Gu zhengyu.gu at oracle.com
Thu Jun 26 17:57:32 UTC 2014

Hi Neil,

There is still an issue. Apparently, you can NOT free the buffer for the environment variable.

678 char * pbuf = (char*)JLI_MemAlloc(pbuflen); 679 JLI_Snprintf(pbuf, pbuflen, "%s%d=%s", NMT_Env_Name, JLI_GetPid(), value); 680 retval = JLI_PutEnv(pbuf); 681 if (JLI_IsTraceLauncher()) { 682 char* envName; 683 char* envBuf; 684 685 // ensures that malloc successful 686 envName = (char*)JLI_MemAlloc(pbuflen); 687 JLI_Snprintf(envName, pbuflen, "%s%d", NMT_Env_Name, JLI_GetPid()); 688 689 printf("TRACER_MARKER: NativeMemoryTracking: env var is %s\n",envName); 690 printf("TRACER_MARKER: NativeMemoryTracking: putenv arg %s\n",pbuf); 691 envBuf = getenv(envName); 692 printf("TRACER_MARKER: NativeMemoryTracking: got value %s\n",envBuf); 693 free(envName); 694 } 695 696 free(pbuf); <<<<=== can not free this buffer 697 }

You can experiment it move #696 to #681, you will see the test to fail.

Linux putenv document says:

putenvis very widely available, but it might or might not copy its argument, risking memory leaks.

Thanks,

-Zhengyu

On 6/25/2014 4:40 PM, Neil Toda wrote:

Okay, Very glad you checked. It really does need to go as early as your prototype suggested. I'll get right on it. -neil On 6/25/2014 12:05 PM, Zhengyu Gu wrote: Hi Neil,

I tried out this patch with my hotspot, it does not work. The reason is that, the environment variable is setup too late, it has to be set before it launches JavaVM (before calling LoadJavaVM()) method. Thanks, -Zhengyu On 6/25/2014 1:58 PM, Neil Toda wrote: Sorry. One more webrev .. 06

http://cr.openjdk.java.net/~ntoda/8042469/webrev-06/ Kumar's nit was correct and in fact index was old and should have been removed allowing .contains member to be used instead of .indexOf. So cleaned up a bit more as can be seen below. Other of Kumar's nits done. Thanks Kumar. webrev-06 102 // get the PID from the env var we set for the JVM 103 String envVarPid = null; 104 for (String line : tr.testOutput) { 105 if (line.contains(envVarPidString)) { 106 int sindex = envVarPidString.length(); 107 envVarPid = line.substring(sindex); 108 break; 109 } 110 } 111 // did we find envVarPid? 112 if (envVarPid == null) { 113 System.out.println(tr); 114 throw new RuntimeException("Error: failed to find env Var Pid in tracking info"); 115 }

webrev-05 102 // get the PID from the env var we set for the JVM 103 haveLauncherPid = false; 104 String envVarPid = null; 105 for (String line : tr.testOutput) { 106 int index; 107 if ((index = line.indexOf(envVarPidString)) >= 0) { 108 int sindex = envVarPidString.length(); 109 envVarPid = line.substring(sindex); 110 haveLauncherPid = true; 111 break; 112 } 113 } 114 // did we find envVarPid? 115 if (!haveLauncherPid) { 116 System.out.println(tr); 117 throw new RuntimeException("Error: failed to find env Var Pid in tracking info"); 118 } On 6/24/2014 2:28 PM, Neil Toda wrote: New webrev-05 with Kumar's comments except for the "C'ish" style. Explained below. http://cr.openjdk.java.net/~ntoda/8042469/webrev-05/ 105 : DONE 146: DONE 168: DONE 106: Your suggestion was the way I had originally coded it for Linux. However on Windows/Cygwin, the code will not compile There is some interaction with the doExec() preceeding it and the fact that it is a varlist. This coding was the simplest workaround. Thanks for the nits Kumar.

On 6/24/2014 5:36 AM, Kumar Srinivasan wrote: Neil, Some nits: TestSpecialArgs.java: extra space 105 for ( String line : tr.testOutput) {

This is very C'ish, I suggest. -106 int index; -107 if ((index = line.indexOf(envVarPidString)) >= 0) { +106 int index = line.indexOf(envVarPidString); +107 if (index >= 0) { Needs space -146 launcherPid = line.substring(sindex,tindex); +146 launcherPid = line.substring(sindex, tindex); Needs space -168 if (!tr.contains("NativeMemoryTracking: got value "+NMTOptionValue)) { +168 if (!tr.contains("NativeMemoryTracking: got value " + NMTOptionValue)) { Thanks Kumar On 6/23/2014 10:26 AM, Neil Toda wrote: I've spun a new webrev based on the comments for webrev-03: http://cr.openjdk.java.net/~ntoda/8042469/webrev-04/ Changes are: 1) java.c a) add free(envName) line 1063 b) change from malloc() to JLIMemAlloc() @ lines 1048 and 1056 Thanks -neil On 6/20/2014 4:45 PM, Kumar Srinivasan wrote: Neil, Generally looks good, yes JLI* functions must be used, I missed that one. Are you going to post another iteration ? Kumar On 6/20/2014 4:27 PM, Neil Toda wrote: Thanks Joe. It would have checked for NULL for me. I'll use the JLI wrapper. -neil On 6/20/2014 4:04 PM, Joe Darcy wrote: Memory allocation in the launcher should use one of the JLIMemAlloc wrappers, if possible. -Joe

On 06/20/2014 09:50 AM, Neil Toda wrote: They should complain. Thanks Zhengyu. I'll make sure these are non-null. -neil On 6/20/2014 5:01 AM, Zhengyu Gu wrote: Neil, Thanks for quick implementation. java.c: Did not check return values of malloc(), I wonder if source code analyzers will complain. -Zhengyu On 6/19/2014 8:29 PM, Neil Toda wrote: Launcher support for modified Native Memory Tracking mechanism in JVM in JDK9. Webrev : http://cr.openjdk.java.net/~ntoda/8042469/webrev-03/ bug : https://bugs.openjdk.java.net/browse/JDK-8042469 CCC : http://ccc.us.oracle.com/8042469 Thanks. -neil

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