JDK-7090324: gclog rotation via external tool (original) (raw)

Erik Helin erik.helin at oracle.com
Wed Jan 29 15:13:46 UTC 2014

Hi Yasumasa,

(have to use HTML email to get a width of more than 78 chars, sorry)

why did you change the code in arguments.cpp in the method check_gc_log_consistency?

Next, the gcLogFileStream::rotate_log method now does a lot of things. Could you separate out the first block into a new method, gcLogFileStream::should_rotate(bool force)?

This was, the code would read:

bool gcLogFileStream::should_rotate(bool force) { return force || _bytes_writen >= GCLogFileSize; }

void gcLogFileStream::rotate_log(bool force) { char time_msg[FILENAMEBUFLEN]; char time_str[EXTRACHARLEN]; char current_file_name[FILENAMEBUFLEN]; char renamed_file_name[FILENAMEBUFLEN];

if (!should_rotate(force)) { return; }

... }

Could you please update your patch?

There is a new empty line in the rotate_log method:

} + #ifdef ASSERT

could you please remove it?

The logging change in rotate_log uses a different kind of if/else syntax than the rest of the file:

if (force) { ... } else { ... }

The other if/else statements in the file uses:

if (cond) { ... } else { ... }

Could you please update your change to use the same if/else syntax?

This part of the change duplicates the code:

request has been received. Saved as %s\n",

sizeof(time_str)),

reached the" " maximum size. Saved as %s\n",

sizeof(time_str)),

sizeof(time_str)), renamed_file_name);

Could you instead just change the message, as in:

const char* msg = forced ? "%s GC log rotation request has been received. Saved as %s\n" : "%s GC log file has reached the maximum size. Saved as %s\n"; jio_snprintf(msg, os::local_time_string((char *)time_str, sizeof(time_str)), renamed_file_name);

The declaration of rotate_log in ostream.hpp still uses the old variable name is_force, it should use force, just as the definition.

Finally, could you add a test that tests your change? Have a look at the other tests in hotspot/test/gc to see how you can do it (you might want to use some functionality from hotspot/test/testlibrary).

Thanks, Erik

On 2014-01-29 15:28, Yasumasa Suenaga wrote:

Hi Staffan,

Thank you for reviewing! I've uploaded new webrev. http://cr.openjdk.java.net/~ysuenaga/JDK-7090324/webrev.01/ On 2014/01/29 20:56, Staffan Larsen wrote: Yasumasa,

src/share/vm/runtime/arguments.cpp no comments src/share/vm/runtime/safepoint.cpp I was surprised that gc log size was checked after each safe point. That seems an uneccssary burden to place on a safe point. Instead we should switch to a periodic task that checks the gc log size. However, this is unrelated to you patch, so please ignore for now. Agree. However, I think that PeriodicTask also is not appropriate for this. Size of GC log file is increased when GC is occurred. So I think rotate function should be called at entry of each GC events e.g. VMGCOperation::doitprologue() etc... src/share/vm/runtime/vmoperations.hpp line 402: nit: missing space before { Fixed. line 405: I think ‘force’ is a better name than ‘isforce’ I removed "force" option from DCmd. So I removed this from VMOperation. src/share/vm/services/diagnosticCommand.cpp line 666: What does this do without the -force option? It looks to me that the non-force case will happen after each safe point (see above) and that there is no need to ever do this from a diagnostic command. Can we remove the option? Indeed. I removed "force" option. line 677: “Target VM does not support GC log file rotation." Fixed. nits: some missing spaces before ‘{' and after ‘if' Fixed. src/share/vm/services/diagnosticCommand.hpp I think RotateGCLogDCmd should require the “control” permission when executed via JMX, so please add: static const JavaPermission permission() { JavaPermission p = {"java.lang.management.ManagementPermission", "control", NULL}; return p; } Added. line 394: Maybe “Force the GC log file to be rotated.” is a better description? Fixed. src/share/vm/utilities/ostream.cpp line 662: I think ‘force’ is a better name than ‘isforce’ line 668: The comment says exactly the same thing as the code so I think it can be skipped line 671: “GC log file rotation occurs by external trigger ONLY." line 675: "not need” -> “no need” line 718: "GC log rotation request has been received” Fixed them. Thanks, Yasumasa src/share/vm/utilities/ostream.hpp no comments

Thanks, /Staffan On 24 jan 2014, at 14:50, Yasumasa Suenaga<yasu at ysfactory.dip.jp> wrote: Hi all, I've created webrev: http://cr.openjdk.java.net/~ysuenaga/JDK-7090324/webrev.00/ This patch works fine on current jdk9/hs-rt . Could you review this?

I am just an Author. So I need a sponsor. Could you help me? Please cooperate. Thanks, Yasumasa On 2013/12/06 0:05, Yasumasa Suenaga wrote: Hi all, Did someone read my email? I really hope to merge "JDK-7090324: gclog rotation via external tool" . I hear that someone need this RFE. So I want to discuss about this.

Thanks, Yasumasa On 2013/11/08 21:47, Yasumasa Suenaga wrote: Hi all, Did someone read my mail? I think that this RFE helps us to watch Java heap on production system. Also I think this RFE is able to be part of the JEP 158 (Unified JVM Logging) . I want to update this RFE in JDK Bug System, but I don't have account. So I've posted email at first.

Thanks, Yasumasa On 2013/09/30 21:10, Yasumasa Suenaga wrote: In previous email, I've attached new patch for this RFE. It works fine with current hsx.

Yasumasa On 2013/09/29 23:40, Yasu wrote: Hi all, We are using "logrotate" tool on RHEL for various log rotation. Current HotSpot has gclog rotation function for log size base, however I need to rotate gc log synchronizing with logrotate tool. So I've created RFE as "JDK-7090324: gclog rotation via external tool" . And Sr. Engineering Manager in Oracle said he use the essence of my patch in one of the jcmd subcommands. http://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2011-September/003274.html

2 years ago, I posted a patch for this RFE. But this patch is too old to apply for current HotSpot. In last month, a similar discussion was appeared in ML. So I think it's time to discuss this RFE. http://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2013-August/008029.html

Please cooperate. Best regards, Yasumasa

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