fatal error: thread exhaustion

runtime stack:
runtime.throw(0x1437109, 0x11)
	GOROOT/src/runtime/panic.go:1117 +0x72 fp=0xc03868de60 sp=0xc03868de30 pc=0x438072
runtime.checkmcount()
	GOROOT/src/runtime/proc.go:701 +0xac fp=0xc03868de88 sp=0xc03868de60 pc=0x43bdac
runtime.mReserveID(0xc000106000)
	GOROOT/src/runtime/proc.go:717 +0x3e fp=0xc03868deb0 sp=0xc03868de88 pc=0x43bdfe
runtime.startm(0x0, 0xc03868df01)
	GOROOT/src/runtime/proc.go:2370 +0x92 fp=0xc03868def8 sp=0xc03868deb0 pc=0x43edf2
runtime.wakep()
	GOROOT/src/runtime/proc.go:2477 +0x66 fp=0xc03868df18 sp=0xc03868def8 pc=0x43f406
runtime.resetspinning()
	GOROOT/src/runtime/proc.go:3020 +0x59 fp=0xc03868df38 sp=0xc03868df18 pc=0x440e59
runtime.schedule()
	GOROOT/src/runtime/proc.go:3176 +0x2b9 fp=0xc03868dfa0 sp=0xc03868df38 pc=0x4414f9
runtime.park_m(0xc031a3f200)
	GOROOT/src/runtime/proc.go:3318 +0x9d fp=0xc03868dfd0 sp=0xc03868dfa0 pc=0x441a9d
runtime.mcall(0x0)
	src/runtime/asm_amd64.s:327 +0x5b fp=0xc03868dfe0 sp=0xc03868dfd0 pc=0x470b3b