Space in Cache but n_lru_nuked statistic growing

Andy Lightfoot Andy.Lightfoot at ig.com
Tue Nov 19 14:31:22 CET 2013


 Hi there,

We have recently increase the size of our file based cache to 50Gb to cope with a significant increase in the content we need to cache.

However, even though there is plenty of free space in the cache the n_lru_nuked stat is growing.

I thought that this would only be the case if there was not sufficient space in the cache (but there appears to be over 14GB free in the cache and we have plenty of disk space on the partition that contains the cache).



We are using Varnish 3.0.3 on RHEL6.



Any ideas why the n_lru_nuked stat is rising?



This is the output of varnishstat

client_conn            4411215        13.94 Client connections accepted

client_drop                  0         0.00 Connection dropped, no sess/wrk

client_req            11657777        36.84 Client requests received

cache_hit              5692984        17.99 Cache hits

cache_hitpass              267         0.00 Cache hits for pass

cache_miss             4606906        14.56 Cache misses

backend_conn            180865         0.57 Backend conn. success

backend_unhealthy         4298         0.01 Backend conn. not attempted

backend_busy                 0         0.00 Backend conn. too many

backend_fail                 0         0.00 Backend conn. failures

backend_reuse          5316479        16.80 Backend conn. reuses

backend_toolate         158949         0.50 Backend conn. was closed

backend_recycle        5475442        17.30 Backend conn. recycles

backend_retry              314         0.00 Backend conn. retry

fetch_head                   1         0.00 Fetch head

fetch_length           2763177         8.73 Fetch with Length

fetch_chunked          2733682         8.64 Fetch chunked

fetch_eof                    0         0.00 Fetch EOF

fetch_bad                    0         0.00 Fetch had bad headers

fetch_close                  0         0.00 Fetch wanted close

fetch_oldhttp                0         0.00 Fetch pre HTTP/1.1 closed

fetch_zero                   0         0.00 Fetch zero len

fetch_failed                10         0.00 Fetch failed

fetch_1xx                    0         0.00 Fetch no body (1xx)

fetch_204                    0         0.00 Fetch no body (204)

fetch_304                   17         0.00 Fetch no body (304)

n_sess_mem                 141          .   N struct sess_mem

n_sess                      52          .   N struct sess

n_object                707545          .   N struct object

n_vampireobject              0          .   N unresurrected objects

n_objectcore            707577          .   N struct objectcore

n_objecthead            278199          .   N struct objecthead

n_waitinglist           509915          .   N struct waitinglist

n_vbc                       14          .   N struct vbc

n_wrk                      100          .   N worker threads

n_wrk_create               102         0.00 N worker threads created

n_wrk_failed                 0         0.00 N worker threads not created

n_wrk_max                    0         0.00 N worker threads limited

n_wrk_lqueue                 0         0.00 work request queue length

n_wrk_queued                 0         0.00 N queued work requests

n_wrk_drop                   0         0.00 N dropped work requests

n_backend                    3          .   N backends

n_expired                 2015          .   N expired objects

n_lru_nuked            3893293          .   N LRU nuked objects

n_lru_moved            1569381          .   N LRU moved objects

losthdr                      0         0.00 HTTP header overflows

n_objsendfile                0         0.00 Objects sent with sendfile

n_objwrite            10710522        33.84 Objects sent with write

n_objoverflow                0         0.00 Objects overflowing workspace

s_sess                 4411215        13.94 Total Sessions

s_req                 11657777        36.84 Total Requests

s_pipe                       0         0.00 Total pipe

s_pass                  894489         2.83 Total pass

s_fetch                5496867        17.37 Total fetch

s_hdrbytes          3296529604     10416.13 Total header bytes

s_bodybytes       148093689394    467935.68 Total body bytes

sess_closed            1178668         3.72 Session Closed

sess_pipeline                0         0.00 Session Pipeline

sess_readahead               0         0.00 Session Read Ahead

sess_linger           11189500        35.36 Session Linger

sess_herd              9372758        29.62 Session herd

shm_records          814659170      2574.10 SHM records

shm_writes            46456055       146.79 SHM writes

shm_flushes                  0         0.00 SHM flushes due to overflow

shm_cont                 26661         0.08 SHM MTX contention

shm_cycles                 341         0.00 SHM cycles through buffer

sms_nreq                  4528         0.01 SMS allocator requests

sms_nobj                     0          .   SMS outstanding allocations

sms_nbytes                   0          .   SMS outstanding bytes

sms_balloc             1897232          .   SMS bytes allocated

sms_bfree              1897232          .   SMS bytes freed

backend_req            5497344        17.37 Backend requests made

n_vcl                        1         0.00 N vcl total

n_vcl_avail                  1         0.00 N vcl available

n_vcl_discard                0         0.00 N vcl discarded

n_ban                        1          .   N total active bans

n_ban_gone                   1          .   N total gone bans

n_ban_add                    1         0.00 N new bans added

n_ban_retire                 0         0.00 N old bans deleted

n_ban_obj_test               0         0.00 N objects tested

n_ban_re_test                0         0.00 N regexps tested against

n_ban_dups                   0         0.00 N duplicate bans removed

hcb_nolock            10300157        32.55 HCB Lookups without lock

hcb_lock               1174513         3.71 HCB Lookups with lock

hcb_insert             1174512         3.71 HCB Inserts

esi_errors                   0         0.00 ESI parse errors (unlock)

esi_warnings                 0         0.00 ESI parse warnings (unlock)

accept_fail                  0         0.00 Accept failures

client_drop_late             0         0.00 Connection dropped late

uptime                  316483         1.00 Client uptime

dir_dns_lookups           1051         0.00 DNS director lookups

dir_dns_failed               0         0.00 DNS director failed lookups

dir_dns_hit            1869574         5.91 DNS director cached lookups hit

dir_dns_cache_full           0         0.00 DNS director full dnscache

vmods                        0          .   Loaded VMODs

n_gzip                       0         0.00 Gzip operations

n_gunzip              12123851        38.31 Gunzip operations

LCK.sms.creat                1         0.00 Created locks

LCK.sms.destroy              0         0.00 Destroyed locks

LCK.sms.locks            13584         0.04 Lock Operations

LCK.sms.colls                0         0.00 Collisions

LCK.smp.creat                0         0.00 Created locks

LCK.smp.destroy              0         0.00 Destroyed locks

LCK.smp.locks                0         0.00 Lock Operations

LCK.smp.colls                0         0.00 Collisions

LCK.sma.creat                1         0.00 Created locks

LCK.sma.destroy              0         0.00 Destroyed locks

LCK.sma.locks          3009407         9.51 Lock Operations

LCK.sma.colls                0         0.00 Collisions

LCK.smf.creat                1         0.00 Created locks

LCK.smf.destroy              0         0.00 Destroyed locks

LCK.smf.locks         26428567        83.51 Lock Operations

LCK.smf.colls                0         0.00 Collisions

LCK.hsl.creat                0         0.00 Created locks

LCK.hsl.destroy              0         0.00 Destroyed locks

LCK.hsl.locks                0         0.00 Lock Operations

LCK.hsl.colls                0         0.00 Collisions

LCK.hcb.creat                1         0.00 Created locks

LCK.hcb.destroy              0         0.00 Destroyed locks

LCK.hcb.locks          2073113         6.55 Lock Operations

LCK.hcb.colls                0         0.00 Collisions

LCK.hcl.creat                0         0.00 Created locks

LCK.hcl.destroy              0         0.00 Destroyed locks

LCK.hcl.locks                0         0.00 Lock Operations

LCK.hcl.colls                0         0.00 Collisions

LCK.vcl.creat                1         0.00 Created locks

LCK.vcl.destroy              0         0.00 Destroyed locks

LCK.vcl.locks           629200         1.99 Lock Operations

LCK.vcl.colls                0         0.00 Collisions

LCK.stat.creat               1         0.00 Created locks

LCK.stat.destroy             0         0.00 Destroyed locks

LCK.stat.locks         4411304        13.94 Lock Operations

LCK.stat.colls               0         0.00 Collisions

LCK.sessmem.creat            1         0.00 Created locks

LCK.sessmem.destroy            0         0.00 Destroyed locks

LCK.sessmem.locks        4493280        14.20 Lock Operations

LCK.sessmem.colls              0         0.00 Collisions

LCK.wstat.creat                1         0.00 Created locks

LCK.wstat.destroy              0         0.00 Destroyed locks

LCK.wstat.locks           638013         2.02 Lock Operations

LCK.wstat.colls                0         0.00 Collisions

LCK.herder.creat               1         0.00 Created locks

LCK.herder.destroy             0         0.00 Destroyed locks

LCK.herder.locks               1         0.00 Lock Operations

LCK.herder.colls               0         0.00 Collisions

LCK.wq.creat                   2         0.00 Created locks

LCK.wq.destroy                 0         0.00 Destroyed locks

LCK.wq.locks            22757276        71.91 Lock Operations

LCK.wq.colls                   0         0.00 Collisions

LCK.objhdr.creat         1174563         3.71 Created locks

LCK.objhdr.destroy        896364         2.83 Destroyed locks

LCK.objhdr.locks        52930423       167.25 Lock Operations

LCK.objhdr.colls               0         0.00 Collisions

LCK.exp.creat                  1         0.00 Created locks

LCK.exp.destroy                0         0.00 Destroyed locks

LCK.exp.locks            8814491        27.85 Lock Operations

LCK.exp.colls                  0         0.00 Collisions

LCK.lru.creat                  2         0.00 Created locks

LCK.lru.destroy                0         0.00 Destroyed locks

LCK.lru.locks            8496146        26.85 Lock Operations

LCK.lru.colls                  0         0.00 Collisions

LCK.cli.creat                  1         0.00 Created locks

LCK.cli.destroy                0         0.00 Destroyed locks

LCK.cli.locks             105440         0.33 Lock Operations

LCK.cli.colls                  0         0.00 Collisions

LCK.ban.creat                  1         0.00 Created locks

LCK.ban.destroy                0         0.00 Destroyed locks

LCK.ban.locks            8814517        27.85 Lock Operations

LCK.ban.colls                  0         0.00 Collisions

LCK.vbp.creat                  1         0.00 Created locks

LCK.vbp.destroy                0         0.00 Destroyed locks

LCK.vbp.locks             315703         1.00 Lock Operations

LCK.vbp.colls                  0         0.00 Collisions

LCK.vbe.creat                  1         0.00 Created locks

LCK.vbe.destroy                0         0.00 Destroyed locks

LCK.vbe.locks             361716         1.14 Lock Operations

LCK.vbe.colls                  0         0.00 Collisions

LCK.backend.creat              3         0.00 Created locks

LCK.backend.destroy            0         0.00 Destroyed locks

LCK.backend.locks       11497749        36.33 Lock Operations

LCK.backend.colls              0         0.00 Collisions

SMF.s0.c_req            13566962        42.87 Allocator requests

SMF.s0.c_fail            3893293        12.30 Allocator failures

SMF.s0.c_bytes      639411638272   2020366.46 Bytes allocated

SMF.s0.c_freed      624779067392   1974131.52 Bytes freed

SMF.s0.g_alloc           1414918          .   Allocations outstanding

SMF.s0.g_bytes       14632570880          .   Bytes outstanding

SMF.s0.g_space       14229925888          .   Bytes available

SMF.s0.g_smf             1542019          .   N struct smf

SMF.s0.g_smf_frag         127100          .   N small free smf

SMF.s0.g_smf_large             1          .   N large free smf

SMA.Transient.c_req      1304195         4.12 Allocator requests

SMA.Transient.c_fail           0         0.00 Allocator failures

SMA.Transient.c_bytes  54287399829    171533.38 Bytes allocated

SMA.Transient.c_freed  54287399829    171533.38 Bytes freed

SMA.Transient.g_alloc            0          .   Allocations outstanding

SMA.Transient.g_bytes            0          .   Bytes outstanding

SMA.Transient.g_space            0          .   Bytes available



Thanks

Andy

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