// map from Ps to their batch offsets
	batchOffsets map[int32][]batchOffset
	stacks       map[uint32][]uint64
	stacksData   []uint64
	ticksPerSec  int64
	pcs          map[uint64]Frame
	cpuSamples   []Event
	timerGoids   map[uint64]bool

	// state for readRawEvent
	args []uint64

	// state for parseEvent
	lastTs Timestamp
	lastG  uint64
	// map from Ps to the last Gs that ran on them
	lastGs map[int32]uint64