How to find out what's accessing a particular hard drive on Windows?

Question

I am trying to tune G1 GC. Application run for sometimes then heap gets full but it shows regions of Eden, survivor and old is 0 and the full GC get called to free up space.

Flags I used: Xmx:30G -XX:+UseG1GC -XX:+AlwaysPreTouch -XX:+UseStringDeduplication -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+ExplicitGCInvokesConcurrent -XX:+ParallelRefProcEnabled -XX:MaxGCPauseMillis=200 -XX:ParallelGCThreads=12 -XX:ConcGCThreads=4

GC LOG:

    {Heap before GC invocations=629 (full 0):
 garbage-first heap   total 31457280K, used 31434556K [0x0000000080000000, 0x0000000080807800, 0x0000000800000000)
  region size 8192K, 0 young (0K), 0 survivors (0K)
 Metaspace       used 41962K, capacity 42424K, committed 42956K, reserved 1087488K
  class space    used 4589K, capacity 4749K, committed 4812K, reserved 1048576K
2017-12-07T14:47:41.979+0000: [GC pause (G1 Evacuation Pause) (young)
Desired survivor size 100663296 bytes, new threshold 15 (max 15)
 18116.906: [G1Ergonomics (CSet Construction) start choosing CSet, _pending_cards: 0, predicted base time: 48.13 ms, remaining time: 151.87 ms, target pause time: 200.00 ms]
 18116.906: [G1Ergonomics (CSet Construction) add young regions to CSet, eden: 0 regions, survivors: 0 regions, predicted young region time: 0.00 ms]
 18116.906: [G1Ergonomics (CSet Construction) finish choosing CSet, eden: 0 regions, survivors: 0 regions, old: 0 regions, predicted pause time: 48.13 ms, target pause time: 200.00 ms]
2017-12-07T14:47:41.981+0000: [SoftReference, 0 refs, 0.0004177 secs]2017-12-07T14:47:41.981+0000: [WeakReference, 0 refs, 0.0002174 secs]2017-12-07T14:47:41.981+0000: [FinalReference, 0 refs, 0.0003298 secs]2017-12-07T14:47:41.982+0000: [PhantomReference, 0 refs, 0 refs, 0.0004635 secs]2017-12-07T14:47:41.982+0000: [JNI Weak Reference, 0.0000152 secs], 0.0439856 secs]
   [Parallel Time: 1.4 ms, GC Workers: 12]
      [GC Worker Start (ms): Min: 18116906.3, Avg: 18116906.3, Max: 18116906.4, Diff: 0.1]
      [Ext Root Scanning (ms): Min: 0.5, Avg: 0.6, Max: 0.9, Diff: 0.4, Sum: 6.9]
      [Update RS (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.1]
         [Processed Buffers: Min: 0, Avg: 0.1, Max: 1, Diff: 1, Sum: 1]
      [Scan RS (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.0]
      [Code Root Scanning (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.0]
      [Object Copy (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.4]
      [Termination (ms): Min: 0.0, Avg: 0.6, Max: 0.7, Diff: 0.7, Sum: 6.8]
         [Termination Attempts: Min: 1, Avg: 1.0, Max: 1, Diff: 0, Sum: 12]
      [GC Worker Other (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.1]
      [GC Worker Total (ms): Min: 1.2, Avg: 1.2, Max: 1.3, Diff: 0.1, Sum: 15.0]
      [GC Worker End (ms): Min: 18116907.6, Avg: 18116907.6, Max: 18116907.6, Diff: 0.0]
   [Code Root Fixup: 0.1 ms]
   [Code Root Purge: 0.0 ms]
   [String Dedup Fixup: 39.9 ms, GC Workers: 12]
      [Queue Fixup (ms): Min: 0.0, Avg: 11.3, Max: 18.1, Diff: 18.1, Sum: 135.1]
      [Table Fixup (ms): Min: 21.7, Avg: 27.8, Max: 35.2, Diff: 13.5, Sum: 333.3]
   [Clear CT: 0.1 ms]
   [Other: 2.5 ms]
      [Choose CSet: 0.0 ms]
      [Ref Proc: 1.6 ms]
      [Ref Enq: 0.1 ms]
      [Redirty Cards: 0.1 ms]
      [Humongous Register: 0.2 ms]
      [Humongous Reclaim: 0.0 ms]
      [Free CSet: 0.1 ms]
   [Eden: 0.0B(1536.0M)->0.0B(1536.0M) Survivors: 0.0B->0.0B Heap: 30.0G(30.0G)->30.0G(30.0G)]
Heap after GC invocations=630 (full 0):
 garbage-first heap   total 31457280K, used 31434556K [0x0000000080000000, 0x0000000080807800, 0x0000000800000000)
  region size 8192K, 0 young (0K), 0 survivors (0K)
 Metaspace       used 41962K, capacity 42424K, committed 42956K, reserved 1087488K
  class space    used 4589K, capacity 4749K, committed 4812K, reserved 1048576K
}
 [Times: user=0.49 sys=0.01, real=0.05 secs] 
{Heap before GC invocations=630 (full 0):
 garbage-first heap   total 31457280K, used 31434556K [0x0000000080000000, 0x0000000080807800, 0x0000000800000000)
  region size 8192K, 0 young (0K), 0 survivors (0K)
 Metaspace       used 41962K, capacity 42424K, committed 42956K, reserved 1087488K
  class space    used 4589K, capacity 4749K, committed 4812K, reserved 1048576K
2017-12-07T14:47:42.024+0000: [GC pause (G1 Evacuation Pause) (young)
Desired survivor size 100663296 bytes, new threshold 15 (max 15)
 18116.952: [G1Ergonomics (CSet Construction) start choosing CSet, _pending_cards: 0, predicted base time: 47.06 ms, remaining time: 152.94 ms, target pause time: 200.00 ms]
 18116.952: [G1Ergonomics (CSet Construction) add young regions to CSet, eden: 0 regions, survivors: 0 regions, predicted young region time: 0.00 ms]
 18116.952: [G1Ergonomics (CSet Construction) finish choosing CSet, eden: 0 regions, survivors: 0 regions, old: 0 regions, predicted pause time: 47.06 ms, target pause time: 200.00 ms]
2017-12-07T14:47:42.026+0000: [SoftReference, 0 refs, 0.0003988 secs]2017-12-07T14:47:42.027+0000: [WeakReference, 0 refs, 0.0003844 secs]2017-12-07T14:47:42.027+0000: [FinalReference, 0 refs, 0.0002286 secs]2017-12-07T14:47:42.027+0000: [PhantomReference, 0 refs, 0 refs, 0.0004361 secs]2017-12-07T14:47:42.028+0000: [JNI Weak Reference, 0.0000169 secs], 0.0433898 secs]
   [Parallel Time: 1.5 ms, GC Workers: 12]
      [GC Worker Start (ms): Min: 18116952.0, Avg: 18116952.1, Max: 18116952.1, Diff: 0.1]
      [Ext Root Scanning (ms): Min: 0.7, Avg: 0.8, Max: 0.9, Diff: 0.1, Sum: 9.5]
      [Update RS (ms): Min: 0.0, Avg: 0.0, Max: 0.2, Diff: 0.2, Sum: 0.2]
         [Processed Buffers: Min: 0, Avg: 0.1, Max: 1, Diff: 1, Sum: 1]
      [Scan RS (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.0]
      [Code Root Scanning (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.0]
      [Object Copy (ms): Min: 0.0, Avg: 0.0, Max: 0.1, Diff: 0.1, Sum: 0.5]
      [Termination (ms): Min: 0.0, Avg: 0.4, Max: 0.5, Diff: 0.5, Sum: 5.3]
         [Termination Attempts: Min: 1, Avg: 1.0, Max: 1, Diff: 0, Sum: 12]
      [GC Worker Other (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.1]
      [GC Worker Total (ms): Min: 1.3, Avg: 1.3, Max: 1.4, Diff: 0.1, Sum: 16.1]
      [GC Worker End (ms): Min: 18116953.4, Avg: 18116953.4, Max: 18116953.4, Diff: 0.0]
   [Code Root Fixup: 0.1 ms]
   [Code Root Purge: 0.0 ms]
   [String Dedup Fixup: 39.2 ms, GC Workers: 12]
      [Queue Fixup (ms): Min: 0.0, Avg: 11.4, Max: 15.4, Diff: 15.4, Sum: 136.9]
      [Table Fixup (ms): Min: 23.7, Avg: 27.7, Max: 39.1, Diff: 15.4, Sum: 332.3]
   [Clear CT: 0.1 ms]
   [Other: 2.5 ms]
      [Choose CSet: 0.0 ms]
      [Ref Proc: 1.6 ms]
      [Ref Enq: 0.1 ms]
      [Redirty Cards: 0.1 ms]
      [Humongous Register: 0.2 ms]
      [Humongous Reclaim: 0.0 ms]
      [Free CSet: 0.1 ms]
   [Eden: 0.0B(1536.0M)->0.0B(1536.0M) Survivors: 0.0B->0.0B Heap: 30.0G(30.0G)->30.0G(30.0G)]
Heap after GC invocations=631 (full 0):
 garbage-first heap   total 31457280K, used 31434556K [0x0000000080000000, 0x0000000080807800, 0x0000000800000000)
  region size 8192K, 0 young (0K), 0 survivors (0K)
 Metaspace       used 41962K, capacity 42424K, committed 42956K, reserved 1087488K
  class space    used 4589K, capacity 4749K, committed 4812K, reserved 1048576K
}
 [Times: user=0.49 sys=0.00, real=0.04 secs] 
 18116.996: [G1Ergonomics (Heap Sizing) attempt heap expansion, reason: allocation request failed, allocation request: 16 bytes]
 18116.997: [G1Ergonomics (Heap Sizing) expand the heap, requested expansion amount: 8388608 bytes, attempted expansion amount: 8388608 bytes]
 18116.997: [G1Ergonomics (Heap Sizing) did not expand the heap, reason: heap already fully expanded]
{Heap before GC invocations=631 (full 0):
 garbage-first heap   total 31457280K, used 31434556K [0x0000000080000000, 0x0000000080807800, 0x0000000800000000)
  region size 8192K, 0 young (0K), 0 survivors (0K)
 Metaspace       used 41962K, capacity 42424K, committed 42956K, reserved 1087488K
  class space    used 4589K, capacity 4749K, committed 4812K, reserved 1048576K
2017-12-07T14:47:42.069+0000: [Full GC (Allocation Failure) 2017-12-07T14:48:06.386+0000: [SoftReference, 122 refs, 0.0001069 secs]2017-12-07T14:48:06.386+0000: [WeakReference, 22631 refs, 0.0079235 secs]2017-12-07T14:48:06.394+0000: [FinalReference, 395 refs, 0.0005771 secs]2017-12-07T14:48:06.394+0000: [PhantomReference, 0 refs, 0 refs, 0.0000163 secs]2017-12-07T14:48:06.394+0000: [JNI Weak Reference, 0.0000357 secs] 29G->14G(30G), 53.8180666 secs]
   [Eden: 0.0B(1536.0M)->0.0B(1536.0M) Survivors: 0.0B->0.0B Heap: 30.0G(30.0G)->14.4G(30.0G)], [Metaspace: 41962K->41951K(1087488K)]
Heap after GC invocations=632 (full 1):
 garbage-first heap   total 31457280K, used 15144510K [0x0000000080000000, 0x0000000080807800, 0x0000000800000000)
  region size 8192K, 0 young (0K), 0 survivors (0K)
 Metaspace       used 41951K, capacity 42406K, committed 42956K, reserved 1087488K
  class space    used 4587K, capacity 4746K, committed 4812K, reserved 1048576K
}

Please help me to figure out the problem and how to avoid full GC.

Solution 1

If you're using Windows Vista or newer, try Resource Monitor. Just type resmon into the Start menu search, or open Task Manager and click the "Resource Monitor" button on the Performance tab.

Once in Resource Monitor, go to the Disk tab. There you can see which processes are accessing your disks, and exactly which disks and which files they're accessing.

You can also check out Process Explorer (from Sysinternals). It's a bit more flexible and fully-featured, for instance you can set a filter to show only the processes that are accessing a particular disk or path.

Solution 2

I don’t know of a program that can show you access by percentage (at least not through a built-in function), but if all you need to do is to see what program is heavily accessing the drive, you can use Process Monitor to see all file and folder accessed. You can select the Files filter to see only disk access and right-click anything that seems normal to filter it out to further reduce the clutter and winnow it down to just the unexpected/heavy access:

You can also export the data to a CSV file and open it in another program to graph a chart, but it’s probably much easier just to view the accesses live in the list.

(Personally I much prefer Filemon over ProcMon, but that only works in XP.)

DiskMon which shows direct disk access (i.e., to the disk itself as opposed to any specific files or folders, but it doesn’t show the process doing it.

Comments

[Joe C]

What does the heap dump say?

[Neetesh]

I don't have the heap dump. But stats on new relic which says Heap was full at that time.

[Joan Venge]

Thanks, I see no activity graph on the drive making the noise. I wonder if it's a legitimate seeking sound.

[martineau]

@Joan Venge: No sure of what exactly triggers it, but Windows itself has always periodically accessed all of my HD drives. Also if any HD starts making noises for no apparent reason, it can indicate that it's going bad.

[Joan Venge]

It stopped now. I don't think it was seeking sound. I tried to turn off my thermaltake HDD dock by pressing the button but it didn't turn off. After safely removing the HDD, I plugged the HDD out, and surely then no sound. As soon as I plugged it back, same sound. But now nothing. Really bizarre.

[Jeff Atwood]

Thanks I always forget about resmon! There's task manager (which has gotten a lot better in Windows 10), resource monitor, and perfmon.. so many choices. But resource monitor is GREAT!