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 cannot be 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(at)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(at)ela] [04-03.17:27:13]=# select a.locktype,a.pid,a.relation,a.mode,a.granted,b.relname from pg_locks a,pg_class b 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(at)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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