On a new virtual machine, top shows that a process of mine consumes 100 GB of virtual memory. I've read that it's possible because of overcommit, however, it's a bit too much. I've never seen anything like this, especially in a VM having just 6 GB real memory, 2 GB swap and a single 40 GB HD partition.
The funny process with 101 GB VIRT is Eclipse IDE (started a few minutes ago) and there's another one, WebKitWebProcess with 98 GB VIRT. All other processes have sane VIRT values of about 1-2 GB. All three tools seem to agree on that:
- Is there any good reason for the processes to request that much virtual memory?
- Isn't such behavior detrimental to the system?
- What are the current limits on the total virtual memory?
Linux 4.15.0-38-generic x86_64 GNU/Linux, Linux Mint 19 Tara
Java HotSpot(TM) 64-Bit Server VM (build 25.191-b12, mixed mode)
Version: 2018-09 (4.9.0) Build id: 20180917-1800
The content of /proc//maps starts with
00400000-00401000 r-xp 00000000 08:01 132092 /usr/lib/jvm/java-8-oracle/jre/bin/java 00600000-00601000 r--p 00000000 08:01 132092 /usr/lib/jvm/java-8-oracle/jre/bin/java 00601000-00602000 rw-p 00001000 08:01 132092 /usr/lib/jvm/java-8-oracle/jre/bin/java 014fc000-02ebe000 rw-p 00000000 00:00 0 [heap] c0000000-d0000000 rw-p 00000000 00:00 0 d0000000-100000000 ---p 00000000 00:00 0 100000000-1012c6000 rw-p 00000000 00:00 0 1012c6000-140000000 ---p 00000000 00:00 0 7ef800000000-7ef800004000 rw-p 00000000 00:00 0 7ef800004000-7ef8000ec000 rw-p 00000000 00:00 0 7ef8000ec000-7ef800100000 rw-p 00000000 00:00 0 7ef800100000-7f0800000000 rw-p 00000000 00:00 0 7f0800000000-7f1000000000 ---p 00000000 00:00 0
The last two shown lines line seem to be the culprit as
0x7f0800000000 - 0x7ef800100000 ≈ 68.7e9. From what I've found, it's an unmapped private region with no permissions. That's all I can say....
VIRTis the amount of memory that the process is able to access at the time which can also include memory being used by other processes, etc. That process isn't actually using anywhere near that amount of memory