RFR[9u-dev]: 8146683: check_addr0 should be more efficient

[Cheleswer Sahu]

Hi,

 

Please review the code changes for https://bugs.openjdk.java.net/browse/JDK-8146683 .

 

Webrev link: http://cr.openjdk.java.net/~csahu/8146683/

JBS Link: https://bugs.openjdk.java.net/browse/JDK-8146683

 

Bug Brief: 

While investigating  bug https://bugs.openjdk.java.net/browse/JDK-8144483  it has been observed that "check_addr0() " function  is not written efficiently.

This function is trying to read each "prmap_t" entry in "/proc/self/map" file one by one which is time taking and can cause in long pauses.

 

Solution proposed:

Instead of reading each "prmap_t" entry in "/proc/self/map" file one by one, read the entries in chunks. There can be many entries in "map" file, so I have decided to read these

in chunks of 100  "prmap_t" entries. Reading entries in chunks saves a lot of read calls and results in smaller pause times. 

 

                                                                                                                                                                                 

Regards,

Cheleswer