fatal error: thread exhaustion

runtime stack:
runtime.throw(0x1320b69, 0x11)
	GOROOT/src/runtime/panic.go:1117 +0x72 fp=0xc00014be40 sp=0xc00014be10 pc=0x438072
runtime.checkmcount()
	GOROOT/src/runtime/proc.go:701 +0xac fp=0xc00014be68 sp=0xc00014be40 pc=0x43bdac
runtime.mReserveID(0x1d403b8)
	GOROOT/src/runtime/proc.go:717 +0x3e fp=0xc00014be90 sp=0xc00014be68 pc=0x43bdfe
runtime.startm(0xc000072800, 0x445e00)
	GOROOT/src/runtime/proc.go:2370 +0x92 fp=0xc00014bed8 sp=0xc00014be90 pc=0x43edf2
runtime.handoffp(0xc000072800)
	GOROOT/src/runtime/proc.go:2412 +0x65 fp=0xc00014bf00 sp=0xc00014bed8 pc=0x43f0c5
runtime.retake(0x6af828da160ca9, 0x1)
	GOROOT/src/runtime/proc.go:5372 +0x17d fp=0xc00014bf48 sp=0xc00014bf00 pc=0x44697d
runtime.sysmon()
	GOROOT/src/runtime/proc.go:5280 +0x185 fp=0xc00014bfb0 sp=0xc00014bf48 pc=0x446485
runtime.mstart1()
	GOROOT/src/runtime/proc.go:1306 +0xc8 fp=0xc00014bfd8 sp=0xc00014bfb0 pc=0x43d4a8
runtime.mstart()
	GOROOT/src/runtime/proc.go:1272 +0x6e fp=0xc00014c000 sp=0xc00014bfd8 pc=0x43d3ae