NPE in logs on startup but no apparent effect

I’ve just installed on a Centos 6 Linux machine; it seems to work fine but I see this early in the logs just after startup, immediately before the This copy of Stardog is licensed to... message:

Exception in thread "Stardog-Linux-Memory-Monitor" java.lang.NullPointerException
	at com.complexible.stardog.api.LinuxMemoryMonitor.checkAndReport(LinuxMemoryMonitor.java:98)
	at com.complexible.stardog.api.LinuxMemoryMonitor.run(LinuxMemoryMonitor.java:84)
	at java.lang.Thread.run(Thread.java:745)

Anything to be concerned about?

Hi Conrad,

This is nothing to be concerned about. The Linux memory monitor will not function but it will not change the behavior of Stardog. If possible, can you send the contents of /proc/meminfo on your system?



Thanks Jess; contents of /proc/meminfo below. FWIW, I installed to a different box running Centos 7 and don’t see that exception in the logs.

MemTotal:       49420368 kB
MemFree:        30393360 kB
Buffers:          220368 kB
Cached:         11762064 kB
SwapCached:         9384 kB
Active:          8568688 kB
Inactive:        7952988 kB
Active(anon):    4462688 kB
Inactive(anon):    76572 kB
Active(file):    4106000 kB
Inactive(file):  7876416 kB
Unevictable:           0 kB
Mlocked:               0 kB
SwapTotal:      45969404 kB
SwapFree:       45748688 kB
Dirty:                76 kB
Writeback:             0 kB
AnonPages:       4535780 kB
Mapped:            49348 kB
Shmem:                12 kB
Slab:            2066080 kB
SReclaimable:    1903768 kB
SUnreclaim:       162312 kB
KernelStack:       13792 kB
PageTables:        23928 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:    70679588 kB
Committed_AS:    3869452 kB
VmallocTotal:   34359738367 kB
VmallocUsed:      215324 kB
VmallocChunk:   34359454032 kB
HardwareCorrupted:     0 kB
AnonHugePages:   3028992 kB
HugePages_Total:       0
HugePages_Free:        0
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB
DirectMap4k:        6116 kB
DirectMap2M:     2088960 kB
DirectMap1G:    48234496 kB

Ok, it looks like we’re assuming MemAvailable to be present which was introduced in Linux 3.14. Centos 6 looks to be using Linux 2.6. I’ll make sure we handle this gracefully. Thanks.


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