autovacuum can not remove dead tuples

Hi,all    
  We meet a problem in postgreql 9.5.5.When we run autovacuum or vacuum manually,it always goes " dead row version
cannotbe removed yet".I think it is about Visable MAP,how can we skip the VM,and do the complete vacuum?
 

INFO:  "ela_elifeassist_product": found 0 removable, 187435 nonremovable row versions in 23981 out of 23981 pages
DETAIL:  185659 dead row versions cannot be removed yet.
There were 2993 unused item pointers.
Skipped 0 pages due to buffer pins.
0 pages are entirely empty.
CPU 0.14s/0.10u sec elapsed 0.25 sec.
INFO:  vacuuming "pg_toast.pg_toast_231114"
INFO:  index "pg_toast_231114_index" now contains 35 row versions in 2 pages
DETAIL:  0 index row versions were removed.
0 index pages have been deleted, 0 are currently reusable.
CPU 0.00s/0.00u sec elapsed 0.00 sec.
INFO:  "pg_toast_231114": found 0 removable, 35 nonremovable row versions in 6 out of 6 pages
DETAIL:  0 dead row versions cannot be removed yet.
There were 0 unused item pointers.
Skipped 0 pages due to buffer pins.
0 pages are entirely empty.
CPU 0.00s/0.00u sec elapsed 0.00 sec.
VACUUM
====== End: Tue Apr 3 17:23:31 CST 2018

[postgres:5543@ela] [04-03.17:27:09]=# select pid,state,substr(query,0,100) from pg_stat_activity where query ~
'ela_elifeassist_product';
 
  pid  | state  |                                               substr                                                
-------+--------+-----------------------------------------------------------------------------------------------------
 38726 | active | select pid,state,substr(query,0,100) from pg_stat_activity where query ~ 'ela_elifeassist_product' 
 10482 | idle   | SELECT                                                                                             +
       |        |     t.tablename,                                                                                   +
       |        |     indexname,                                                                                     +
       |        |     c.reltuples AS num_rows,                                                                       +
       |        |     pg_size_pretty(pg_relation_
 26023 | idle   | select * from pg_stat_activity where query like '%ela_elifeassist_product%';
 40180 | active | autovacuum: VACUUM public.ela_elifeassist_product
(4 rows)

Time: 2.919 ms
[postgres:5543@ela] [04-03.17:27:13]=# select a.locktype,a.pid,a.relation,a.mode,a.granted,b.relname from pg_locks
a,pg_classb where a.relation=b.oid and relname='ela_elifeassist_product';
 
 locktype |  pid  | relation |           mode           | granted |         relname         
----------+-------+----------+--------------------------+---------+-------------------------
 relation | 40180 |   231114 | ShareUpdateExclusiveLock | t       | ela_elifeassist_product
(1 row)

Time: 1.056 ms

[postgres:5543@ela] [04-03.17:27:57]=# select relname,relpages,relallvisible from pg_class where relname
='ela_elifeassist_product';
         relname         | relpages | relallvisible 
-------------------------+----------+---------------
 ela_elifeassist_product |    23981 |            18
(1 row)

Time: 8.679 ms


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