Limits

Every limit of xiao.packet, in one place.

Sending

Limit	Value	Behavior
Payload sent	512 bytes	writing past it raises packet payload exceeds 512 bytes; send_raw returns it as an error, send_fields returns packet payload exceeds 512 bytes (<n> encoded)
Pending sends	8 (capacity())	a ninth send returns false, "send queue full, retry next frame"
Wait of a send	2 seconds	dropped when the game sends no packet on the connection in that time
Send order	order of the send calls	each send gets a sequence number, the flush sorts by it
encode and hook replacements	no size limit	only the fields table limits below apply

Values

Limit	Value	Behavior
Packet id	0 to 1023	other ids raise integer out of range
Integers	range of the wire type, no fraction	otherwise integer out of range
64-bit values	exact up to 2^53	fields() gives larger values as decimal strings and the encoder takes them back
Fields table	65536 values, 64 levels deep	fields table has more than 65536 values, fields table nested too deep

Receiving

Limit	Value	Behavior
Packets queued per frame	4096	extra packets are lost and counted by dropped()
Payload captured	64 KiB	longer payloads are cut and msg.complete is false
Receivers of a frame	100 ms, in their own call before the frame callbacks	over it the VM is stopped with script timeout

Hooks

Limit	Value	Behavior
Hooks installed	64	more raise too many packet hooks (64)
Wait for the VM	1 ms	packet passes unchanged, counted in busy
Budget per packet	2 ms, from the packet arrival	packet passes unchanged, counted in overruns
Overruns in a row	3	the hook is removed
Payload	64 KiB	longer payloads pass unchanged
Incoming replacement	size of the receive buffer of the game	longer passes unchanged
Instruction check	every 1000 Lua instructions	budget is tested there

The xiao.cmd callbacks have their own limits, see Threads and time budget.

Packet log copy

Limit	Value	Behavior
Payload copied	4 MiB	PACKET TOO LARGE
Values before the p table	150	past 150 values and enum tables (Copy as Lua) or reads (Copy as receiver), they move to a p table to stay under 200 locals
Enum table	16 names	larger enums only list the names the packet uses
Printed fields	6	Copy as receiver prints the first 6 fields
Inline byte lines	32 bytes per line, runs over 256 bytes	emitted as write_bytes("\x..") lines