Constantly scans for WiFi networks

[pR0Ps]

QSyncthingTray is constantly requesting network scans. This can cause ping spikes (I was seeing up to 150ms on a WiFi connected LAN) and higher battery usage.

The logs below are from /var/log/wifi.log after running /System/Library/PrivateFrameworks/Apple80211.framework/Versions/A/Resources/airport en0 debug +AllUserland to enable debugging on OS X 10.11.6. They show QSyncthingTray scanning 3 times in 13 seconds. This happens constantly as long as the program is running.

EDIT:

Apparently this is a known issue with Qt. See here.

A temporary fix is to set the environment variable QT_BEARER_POLL_TIMEOUT=-1 before launching any Qt applications.

I'll leave it up to you whether you want to just close this as an upstream problem or implement some sort of workaround like this in your application.

Tue Nov 27 02:01:33.764 IPC: <airportd[68]> ADDED XPC CLIENT CONNECTION [QSyncthingTray (pid=14397, euid=501, egid=20)]
Tue Nov 27 02:01:33.765 Info: <airportd[68]> SCAN request received from pid 14397 (QSyncthingTray) with priority 0
Tue Nov 27 02:01:33.766 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 1 does not require a live scan
Tue Nov 27 02:01:33.766 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 2 does not require a live scan
Tue Nov 27 02:01:33.766 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 3 does not require a live scan
Tue Nov 27 02:01:33.766 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 4 does not require a live scan
Tue Nov 27 02:01:33.766 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 5 does not require a live scan
Tue Nov 27 02:01:33.766 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 6 does not require a live scan
Tue Nov 27 02:01:33.766 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray does not require a live scan
Tue Nov 27 02:01:33.766 AutoJoin: <airportd[68]> Successful cache-assisted scan request for QSyncthingTray with channels {(
Tue Nov 27 02:01:33.766     <CWChannel: 0x7f9073514e70> [channelNumber=1(2GHz), channelWidth={20MHz}, active],
Tue Nov 27 02:01:33.766     <CWChannel: 0x7f90735507b0> [channelNumber=2(2GHz), channelWidth={20MHz}, active],
Tue Nov 27 02:01:33.766     <CWChannel: 0x7f9073526370> [channelNumber=3(2GHz), channelWidth={20MHz}, active],
Tue Nov 27 02:01:33.766     <CWChannel: 0x7f9073526420> [channelNumber=4(2GHz), channelWidth={20MHz}, active],
Tue Nov 27 02:01:33.766     <CWChannel: 0x7f907354ddb0> [channelNumber=5(2GHz), channelWidth={20MHz}, active],
Tue Nov 27 02:01:33.766     <CWChannel: 0x7f907354c6c0> [channelNumber=6(2GHz), channelWidth={20MHz}, active]
Tue Nov 27 02:01:33.766 )} took 0.0007 seconds, returned 5 results
Tue Nov 27 02:01:33.767 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 7 does not require a live scan
Tue Nov 27 02:01:33.767 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 8 does not require a live scan
Tue Nov 27 02:01:33.767 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 9 does not require a live scan
Tue Nov 27 02:01:33.767 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 10 does not require a live scan
Tue Nov 27 02:01:33.767 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 11 does not require a live scan
Tue Nov 27 02:01:33.767 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 36 does not require a live scan
Tue Nov 27 02:01:33.767 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray does not require a live scan
Tue Nov 27 02:01:33.767 AutoJoin: <airportd[68]> Successful cache-assisted scan request for QSyncthingTray with channels {(
Tue Nov 27 02:01:33.767     <CWChannel: 0x7f907354ff70> [channelNumber=7(2GHz), channelWidth={20MHz}, active],
Tue Nov 27 02:01:33.767     <CWChannel: 0x7f907351f330> [channelNumber=8(2GHz), channelWidth={20MHz}, active],
Tue Nov 27 02:01:33.767     <CWChannel: 0x7f9073532450> [channelNumber=9(2GHz), channelWidth={20MHz}, active],
Tue Nov 27 02:01:33.767     <CWChannel: 0x7f907350b040> [channelNumber=10(2GHz), channelWidth={20MHz}, active],
Tue Nov 27 02:01:33.767     <CWChannel: 0x7f90735073a0> [channelNumber=11(2GHz), channelWidth={20MHz}, active],
Tue Nov 27 02:01:33.767     <CWChannel: 0x7f9073531f40> [channelNumber=36(5GHz), channelWidth={40MHz(+1)}, active]
Tue Nov 27 02:01:33.767 )} took 0.0008 seconds, returned 6 results
Tue Nov 27 02:01:33.768 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 40 does not require a live scan
Tue Nov 27 02:01:33.768 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 44 does not require a live scan
Tue Nov 27 02:01:33.768 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 48 does not require a live scan
Tue Nov 27 02:01:33.768 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 52 does not require a live scan
Tue Nov 27 02:01:33.768 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 56 does not require a live scan
Tue Nov 27 02:01:33.768 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 60 does not require a live scan
Tue Nov 27 02:01:33.768 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray does not require a live scan
Tue Nov 27 02:01:33.768 AutoJoin: <airportd[68]> Successful cache-assisted scan request for QSyncthingTray with channels {(
Tue Nov 27 02:01:33.768     <CWChannel: 0x7f907354ff30> [channelNumber=40(5GHz), channelWidth={40MHz(-1)}, active],
Tue Nov 27 02:01:33.768     <CWChannel: 0x7f9073530fe0> [channelNumber=44(5GHz), channelWidth={40MHz(+1)}, active],
Tue Nov 27 02:01:33.768     <CWChannel: 0x7f90735409f0> [channelNumber=48(5GHz), channelWidth={40MHz(-1)}, active],
Tue Nov 27 02:01:33.768     <CWChannel: 0x7f90735504e0> [channelNumber=52(5GHz), channelWidth={40MHz(+1)}, active, DFS],
Tue Nov 27 02:01:33.768     <CWChannel: 0x7f9073528030> [channelNumber=56(5GHz), channelWidth={40MHz(-1)}, active, DFS],
Tue Nov 27 02:01:33.768     <CWChannel: 0x7f907354e210> [channelNumber=60(5GHz), channelWidth={40MHz(+1)}, active, DFS]
Tue Nov 27 02:01:33.768 )} took 0.0004 seconds, returned 2 results
Tue Nov 27 02:01:33.769 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 64 does not require a live scan
Tue Nov 27 02:01:33.769 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 149 does not require a live scan
Tue Nov 27 02:01:33.769 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 153 does not require a live scan
Tue Nov 27 02:01:33.769 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 157 does not require a live scan
Tue Nov 27 02:01:33.769 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 161 does not require a live scan
Tue Nov 27 02:01:33.769 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 165 does not require a live scan
Tue Nov 27 02:01:33.769 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray does not require a live scan
Tue Nov 27 02:01:33.769 AutoJoin: <airportd[68]> Successful cache-assisted scan request for QSyncthingTray with channels {(
Tue Nov 27 02:01:33.769     <CWChannel: 0x7f90735331c0> [channelNumber=64(5GHz), channelWidth={40MHz(-1)}, active, DFS],
Tue Nov 27 02:01:33.769     <CWChannel: 0x7f907352cf30> [channelNumber=149(5GHz), channelWidth={40MHz(+1)}, active],
Tue Nov 27 02:01:33.769     <CWChannel: 0x7f907351a180> [channelNumber=153(5GHz), channelWidth={40MHz(-1)}, active],
Tue Nov 27 02:01:33.769     <CWChannel: 0x7f9073522920> [channelNumber=157(5GHz), channelWidth={40MHz(+1)}, active],
Tue Nov 27 02:01:33.769     <CWChannel: 0x7f907351e620> [channelNumber=161(5GHz), channelWidth={40MHz(-1)}, active],
Tue Nov 27 02:01:33.769     <CWChannel: 0x7f90735233e0> [channelNumber=165(5GHz), channelWidth={20MHz}, active]
Tue Nov 27 02:01:33.769 )} took 0.0003 seconds, returned 0 results
Tue Nov 27 02:01:33.769 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 100 does not require a live scan
Tue Nov 27 02:01:33.769 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 104 does not require a live scan
Tue Nov 27 02:01:33.769 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 108 does not require a live scan
Tue Nov 27 02:01:33.769 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 112 does not require a live scan
Tue Nov 27 02:01:33.769 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 116 does not require a live scan
Tue Nov 27 02:01:33.769 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 120 does not require a live scan
Tue Nov 27 02:01:33.769 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray does not require a live scan
Tue Nov 27 02:01:33.769 AutoJoin: <airportd[68]> Successful cache-assisted scan request for QSyncthingTray with channels {(
Tue Nov 27 02:01:33.769     <CWChannel: 0x7f907351ed10> [channelNumber=100(5GHz), channelWidth={40MHz(+1)}, DFS],
Tue Nov 27 02:01:33.770     <CWChannel: 0x7f90735282c0> [channelNumber=104(5GHz), channelWidth={40MHz(-1)}, DFS],
Tue Nov 27 02:01:33.770     <CWChannel: 0x7f9073529300> [channelNumber=108(5GHz), channelWidth={40MHz(+1)}, DFS],
Tue Nov 27 02:01:33.770     <CWChannel: 0x7f9073510280> [channelNumber=112(5GHz), channelWidth={40MHz(-1)}, DFS],
Tue Nov 27 02:01:33.770     <CWChannel: 0x7f9073532dc0> [channelNumber=116(5GHz), channelWidth={40MHz(+1)}, DFS],
Tue Nov 27 02:01:33.770     <CWChannel: 0x7f9073514660> [channelNumber=120(5GHz), channelWidth={40MHz(-1)}, DFS]
Tue Nov 27 02:01:33.770 )} took 0.0003 seconds, returned 0 results
Tue Nov 27 02:01:33.770 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 124 does not require a live scan
Tue Nov 27 02:01:33.770 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 128 does not require a live scan
Tue Nov 27 02:01:33.770 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 132 does not require a live scan
Tue Nov 27 02:01:33.770 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 136 does not require a live scan
Tue Nov 27 02:01:33.770 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 140 does not require a live scan
Tue Nov 27 02:01:33.770 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray on channel 144 does not require a live scan
Tue Nov 27 02:01:33.770 Scan: <airportd[68]> Cache-assisted scan request for QSyncthingTray does not require a live scan
Tue Nov 27 02:01:33.770 AutoJoin: <airportd[68]> Successful cache-assisted scan request for QSyncthingTray with channels {(
Tue Nov 27 02:01:33.770     <CWChannel: 0x7f9075949200> [channelNumber=124(5GHz), channelWidth={20MHz}, DFS],
Tue Nov 27 02:01:33.770     <CWChannel: 0x7f9073550b50> [channelNumber=128(5GHz), channelWidth={40MHz(-1)}, DFS],
Tue Nov 27 02:01:33.770     <CWChannel: 0x7f907350dcd0> [channelNumber=132(5GHz), channelWidth={20MHz}, DFS],
Tue Nov 27 02:01:33.770     <CWChannel: 0x7f9073532890> [channelNumber=136(5GHz), channelWidth={40MHz(-1)}, DFS],
Tue Nov 27 02:01:33.770     <CWChannel: 0x7f90735328a0> [channelNumber=140(5GHz), channelWidth={20MHz}, DFS],
Tue Nov 27 02:01:33.770     <CWChannel: 0x7f907354ecf0> [channelNumber=144(5GHz), channelWidth={40MHz(-1)}, DFS]
Tue Nov 27 02:01:33.770 )} took 0.0004 seconds, returned 0 results
Tue Nov 27 02:01:33.779 IPC: <airportd[68]> INVALIDATED XPC CLIENT CONNECTION [QSyncthingTray (pid=14397, euid=501, egid=20)]
Tue Nov 27 02:01:43.847 IPC: <airportd[68]> ADDED XPC CLIENT CONNECTION [QSyncthingTray (pid=14397, euid=501, egid=20)]
Tue Nov 27 02:01:43.849 Info: <airportd[68]> SCAN request received from pid 14397 (QSyncthingTray) with priority 0
Tue Nov 27 02:01:44.071 Driver Event: <airportd[68]> _bsd_80211_event_callback: SCAN_CACHE_UPDATED (en0)
<snip duplicate channel logs>
Tue Nov 27 02:01:46.741 IPC: <airportd[68]> INVALIDATED XPC CLIENT CONNECTION [QSyncthingTray (pid=14397, euid=501, egid=20)]
Tue Nov 27 02:01:46.755 IPC: <airportd[68]> ADDED XPC CLIENT CONNECTION [QSyncthingTray (pid=14397, euid=501, egid=20)]
Tue Nov 27 02:01:46.756 Info: <airportd[68]> SCAN request received from pid 14397 (QSyncthingTray) with priority 0
<snip duplicate channel logs>
Tue Nov 27 02:01:46.767 IPC: <airportd[68]> INVALIDATED XPC CLIENT CONNECTION [QSyncthingTray (pid=14397, euid=501, egid=20)]