Constant PUT_BACK_BATCH 

const PUT_BACK_BATCH: usize = 200;

How many held files are opened at once, outside the exchanges’ lock, at most, and for how long at most (PUT_BACK_HOLD); they are then placed under it in short holds (in_short_holds), the lock left free a while between two (PUT_BACK_FREE), for whatever exchange waits for it, a dose’s first. Until 18 October 2026 the put back took it again at once, and a dose’s exchange waited up to 14 s for it on a computer; until 20 October 2026 it placed a whole batch in one hold, 1.1 s on CI’s Windows job.