TID: 140665659860736 == 0x7fef46b02700
TID: 140665668343552 == 0x7fef47319700
T9: ID 0x7fef46b02700
T1: ID 0x7fef47319700

T9: log->write_lsn = 3710208
T1: log->write_lsn = 3710848
======
T9: SLOT LSNS:
OLD:
slot_start_lsn = {offset = 3708032, file = 164},
slot_end_lsn = {offset = 3710208, file = 164}

(currently moved on and in __log_wait_for_earlier_slot on a later LSN)
======
T1: SLOT LSNS:
slot_start_lsn = {offset = 3710208, file = 164},
slot_end_lsn = {offset = 3710848, file = 164}
======
DBG array:
(gdb) p dbg[0]@16
$5 = {
{tid = 140665668343552, i = 27, lsn = {l = {offset = 3698944, file = 164}}},
{tid = 140665659860736, i = 28, lsn = {l = {offset = 3700480, file = 164}}},
{tid = 140665659860736, i = 29, lsn = {l = {offset = 3700608, file = 164}}},
{tid = 140665685309184, i = 30, lsn = {l = {offset = 3703296, file = 164}}},
{tid = 140665676826368, i = 31, lsn = {l = {offset = 3705856, file = 164}}},
{tid = 140665685309184, i = 32, lsn = {l = {offset = 3705984, file = 164}}},
{tid = 140665668343552, i = 33, lsn = {l = {offset = 3708032, file = 164}}},
* {tid = 140665659860736, i = 34, lsn = {l = {offset = 3710208, file = 164}}},
* {tid = 140665668343552, i = 35, lsn = {l = {offset = 3710848, file = 164}}},
{tid = 140665659860736, i = 20, lsn = {l = {offset = 3691648, file = 164}}},
{tid = 140665685309184, i = 21, lsn = {l = {offset = 3693824, file = 164}}},
{tid = 140665659860736, i = 22, lsn = {l = {offset = 3694080, file = 164}}},
{tid = 140665676826368, i = 23, lsn = {l = {offset = 3694976, file = 164}}},
{tid = 140665685309184, i = 24, lsn = {l = {offset = 3696128, file = 164}}},
{tid = 140665668343552, i = 25, lsn = {l = {offset = 3697408, file = 164}}},
{tid = 140665676826368, i = 26, lsn = {l = {offset = 3698304, file = 164}}}}

=====
CLOCK SEQUENCE:
  T1: 8481976 log_early1 in log_wait_for_earlier_slot
  T1: log->write_lsn = 3708032
T9: 8498464 log_clock1 before setting log->write_start_lsn
T9: log->write_start_lsn = 3708032
T9: 8498638 log_clock2 before setting log->write_lsn
T9: log->write_lsn = 3710208
  T1: 8499632 log_early2 in log_wait_for_earlier_slot sees log->write-lsn 3710208
  T1: records log->early_lsn2 = log->write_lsn = 3710208
  T1: 8500122 log_clock1 before setting log->write_start_lsn
  T1: log->write_start_lsn = 3710208
  T1: 8500226 log_clock2 before setting log->write_lsn
  T1: log->write_lsn = 3710848
  T1: 8500378 log_clock3 after setting log->write_lsn
  T1: 8500794 log_write1 before WT_ASSERT(session, __wt_log_cmp(&save_lsn, &log->write_lsn) <= 0);
  T1: session->write_lsn1 = 3710848
  T1: 8501000 log_write2 after ASSERT
  T1: session->write_lsn2 = 3710848
*** Sometime after this log->write_lsn gets set back to 3710208 ***
T9: 8513034 log_clock3 after saving log->write_lsn
  T1: 8526470 log_write_internal 'start' of while loop WT_LOG_FLUSH
  T1: sees log->write_lsn = 3710208 hangs

[All 4 threads waiting in log_wait_for_earlier_slot have log_early1 > 8513034]