bitcoin-qt shutdown systematically takes about 5 minutes on my new debian stretch system. A typical debug file looks as follows:
2016-12-20 19:58:55 AcceptToMemoryPool: peer=3: accepted 2b8c3...5c14 (poolsz ...
2016-12-20 19:58:56 AcceptToMemoryPool: peer=3: accepted 4a3d1...7e0e (poolsz ...
2016-12-20 19:58:56 tor: Thread interrupt
2016-12-20 19:58:56 scheduler thread interrupt
2016-12-20 19:58:56 torcontrol thread exit
2016-12-20 19:58:56 opencon thread interrupt
2016-12-20 19:58:56 addcon thread interrupt
2016-12-20 19:58:56 msghand thread interrupt
2016-12-20 19:58:56 net thread interrupt
This is where it hangs for a few minutes, then:
2016-12-20 20:05:58 Imported mempool transactions from disk: 10932 successes, 476 failed, 0 expired
2016-12-20 20:05:58 Shutdown: In progress...
2016-12-20 20:05:58 Stop
2016-12-20 20:05:59 Erased 1 orphan tx from peer 5
2016-12-20 20:06:01 Dumped mempool: 0.063746s to copy, 1.55051s to dump
2016-12-20 20:06:01 Shutdown: done
I have never experienced this behavior before. However, I am dealing with a pre-release test build (v0.13.99.0-8c7947e) on a new version of debian (stretch) on new hardware which is very cheap and very slow. (EDIT: I initially thought this behavior was specific to bitcoin-qt and that bitcoind would shutdown immediately, but I have just had a case of bitcoind taking 5 minutes to shutdown.)
$ uname -a
Linux front 4.8.0-1-amd64 [#1](/bitcoin-bitcoin/1/) SMP Debian 4.8.7-1 (2016-11-13) x86_64 GNU/Linux
$ lscpu
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
CPU(s): 2
On-line CPU(s) list: 0,1
Thread(s) per core: 1
Core(s) per socket: 2
Socket(s): 1
NUMA node(s): 1
Vendor ID: GenuineIntel
CPU family: 6
Model: 76
Model name: Intel(R) Celeron(R) CPU N3050 @ 1.60GHz
Stepping: 3
CPU MHz: 479.980
CPU max MHz: 2160.0000
CPU min MHz: 480.0000
BogoMIPS: 3200.00
Virtualization: VT-x
L1d cache: 24K
L1i cache: 32K
L2 cache: 1024K
NUMA node0 CPU(s): 0,1
Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36
clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm constant_tsc arch_perfmon
pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor
ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm sse4_1 sse4_2 movbe popcnt tsc_deadline_timer aes
rdrand lahf_lm 3dnowprefetch epb tpr_shadow vnmi flexpriority ept vpid tsc_adjust smep erms
dtherm ida arat
$ df -h
Filesystem Size Used Avail Use% Mounted on
udev 3.9G 0 3.9G 0% /dev
tmpfs 790M 18M 772M 3% /run
/dev/mapper/front--vg-root 23G 8.5G 14G 40% /
tmpfs 3.9G 428K 3.9G 1% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup
/dev/mapper/front--vg-var 9.2G 2.2G 6.5G 26% /var
/dev/mapper/front--vg-tmp 1.8G 8.0M 1.7G 1% /tmp
/dev/sda2 237M 38M 187M 17% /boot
/dev/sda1 511M 132K 511M 1% /boot/efi
/dev/mapper/front--vg-home 874G 131G 699G 16% /home
tmpfs 790M 16K 790M 1% /run/user/117
tmpfs 790M 24K 790M 1% /run/user/1000
$ free
total used free shared buff/cache available
Mem: 8083768 1237252 2104880 267092 4741636 6273948
Swap: 8290300 0 8290300
