How to figure out the reason for Azure Cache Redis memory usage pattern?

Kaarlo Räihä 5

We are having a following problem with Azure Cache Redis (basic tier), the memory usage increases steadily and then the evict happens. The issue is that we are not writing any new data to Redis. In total we have eight keys (checked with info keyspace) and the biggest one has about 500 bytes of data in it.

I have attached a log of info memory

info memory

# Memory

used_memory:102750824

used_memory_human:97.99M

used_memory_rss:133332992

used_memory_rss_human:127.16M

used_memory_peak:102936656

used_memory_peak_human:98.17M

used_memory_peak_perc:99.82%

used_memory_overhead:392272

used_memory_startup:289080

used_memory_dataset:102358552

used_memory_dataset_perc:99.90%

used_memory_lua:32768

maxmemory:285000000

maxmemory_reservation:30000000

maxfragmentationmemory_reservation:30000000

maxmemory_desired_reservation:30000000

maxfragmentationmemory_desired_reservation:30000000

maxmemory_human:271.80M

maxmemory_policy:volatile-lru

mem_allocator:jemalloc-4.0.3

azure_redis_memory_increase

ShaktiSingh-MSFT 13,826 Reputation points Microsoft Employee

2023-07-17T08:29:13.46+00:00

Hi
Kaarlo Räihä •,

Welcome to Microsoft Q&A forum and thanks for using Azure Services.

As I understand, you want to know How to figure out the reason for Azure Cache Redis memory usage pattern.

You have mentioned that no new data is added and yet eviction happened.

This is strange and not expected. I would recommend you to please file a support ticket for deeper investigation and in case if you don't have a support plan, do let us know here so that we can check on other options to unblock you. Thanks

Kaarlo Räihä 5

Hi. Thanks for the answer. The customer does not have support plan yet (it is summer vacation time, so getting a one might take some time), but I can share all the info to you via other channels if possible.

It seems that if I run MEMORY MALLOC-STATS then most allocations are in large category

___ Begin jemalloc statistics ___
Version: 4.0.3-0-ge9192eacf8935e29fc62fddc2701f7942b1cc02c
Assertions disabled
Run-time option settings:
  opt.abort: false
  opt.lg_chunk: 22
  opt.dss: "secondary"
  opt.narenas: 1
  opt.lg_dirty_mult: 3 (arenas.lg_dirty_mult: 3)
  opt.stats_print: false
  opt.junk: "false"
  opt.quarantine: 0
  opt.redzone: false
  opt.zero: false
  opt.tcache: true
  opt.lg_tcache_max: 15
CPUs: 1
Arenas: 1
Pointer size: 8
Quantum size: 8
Page size: 4096
Min active:dirty page ratio per arena: 8:1
Maximum thread-cached size class: 32768
Chunk size: 4194304 (2^22)
Allocated: 106790168, active: 127762432, metadata: 5447112, resident: 133009408, mapped: 146800640
Current active ceiling: 130023424

arenas[0]:
assigned threads: 22
dss allocation precedence: disabled
min active:dirty page ratio: 8:1
dirty pages: 31192:131 active:dirty, 1 sweep, 521 madvises, 2305 purged
                            allocated      nmalloc      ndalloc    nrequests
small:                        3018008       103886        46420     34078433
large:                      103772160      1171248      1166195      2306970
huge:                               0            0            0            0
total:                      106790168      1275134      1212615     36385403
active:                     127762432
mapped:                     142606336
metadata: mapped: 3620864, allocated: 740104
bins:           size ind    allocated      nmalloc      ndalloc    nrequests      curregs      curruns regs pgs  util       nfills     nflushes      newruns       reruns
                   8   0        84160        18505         7985      7489198        10520           21  512   1 0.978         6048         3269           21         5204
                  16   1       204416        16204         3428      7085285        12776           51  256   1 0.978         2293         1987           55         1008
                  24   2        71880         9416         6421      9333278         2995            7  512   3 0.835         4257         3234            7         3346
                  32   3         4224          410          278       627813          132            2  128   1 0.515          130          126            2           15
                  40   4         6240          426          270      1141836          156            1  512   5 0.304          113          117            1            0
                  48   5       736176        26323        10986      4870878        15337           60  256   3 0.998         8769         3148           64         8863
                  56   6         1232         1931         1909        14034           22            1  512   7 0.042         1778         1764            1            0
                  64   7         1216         4477         4458      1160457           19            1   64   1 0.296         3481         2759            1            0
                  80   8          880          318          307        24969           11            1  256   5 0.042           15           19            2            1
                  96   9       980640        17702         7487      2280093        10215           80  128   3 0.997         6072         3165          109         6172
                 112  10            0          135          135           98            0            0  256   7 1               29           33           28            0
                 128  11       645888         5104           58         5038         5046          158   32   1 0.998          170           17          159            1
                 160  12          320          118          116        14544            2            1  128   5 0.015            6           10            1            0
                 192  13          960          925          920        10045            5            1   64   3 0.078          854          858            1            0
                 224  14          224          127          126           29            1            1  128   7 0.007           19           24            1            0
                 256  15            0           27           27           18            0            0   16   1 1               11           14           11            0
                 320  16         5120          116          100           34           16            1   64   5 0.250            8           12            1            0
                 384  17          384           50           49           11            1            1   32   3 0.031            9           12            1            0
                 448  18            0           74           74            5            0            0   64   7 1                5            9            5            0
                 512  19          512           16           15            7            1            1    8   1 0.125            4            5            3            0
                 640  20            0           44           44           16            0            0   32   5 1                9           13            9            0
                 768  21            0           18           18            2            0            0   16   3 1                2            4            2            0
                 896  22       115584         1043          914        10027          129            5   32   7 0.806          833          836           16          245
                1024  23         2048           12           10            6            2            1    4   1 0.500            1            3            4            1
                1280  24        85760          254          187         9967           67            5   16   5 0.837           61           63           16            7
                     ---
                1792  26            0           16           16            1            0            0   16   7 1                1            3            1            0
                2048  27         8192           10            6            5            4            2    2   1 1                1            2            5            0
                2560  28         2560           10            9            3            1            1    8   5 0.125            1            2            2            0
                     ---
                4096  31         8192           14           12            4            2            2    1   1 1                2            3           14            0
                5120  32        10240           10            8            4            2            1    4   5 0.500            1            2            3            0
                6144  33         6144            1            0            1            1            1    2   3 0.500            0            0            1            0
                     ---
                8192  35            0           14           14            3            0            0    1   2 1                3            4           14            0
               10240  36        10240           10            9            3            1            1    2   5 0.500            1            2            5            0
               12288  37        24576           26           24          721            2            2    1   3 1               17           18           26            0
                     ---
large:          size ind    allocated      nmalloc      ndalloc    nrequests      curruns
               16384  39        16384            4            3            4            1
               20480  40    102993920         8780         3751      1144502         5029
                     ---
               32768  43       720896           23            1           23           22
               40960  44        40960      1162440      1162439      1162440            1
               49152  45            0            1            1            1            0
                     ---
huge:           size ind    allocated      nmalloc      ndalloc    nrequests   curhchunks
                     ---
--- End jemalloc statistics ---

ShaktiSingh-MSFT 13,826 Reputation points Microsoft Employee

2023-07-17T11:25:57.1466667+00:00

Hi
Kaarlo Räihä •,

Could you send an email to AzCommunity@Microsoft.com with your Subscription ID and thread link to this post, and I will enable a one-time free support request for your subscription.

Please reference this forum thread in the subject: ATTN: SHAKTI - How to figure out the reason for Azure Cache Redis memory usage pattern?

Regards,

Shakti
Kaarlo Räihä 5 Reputation points

2023-09-13T05:44:58.4933333+00:00

Issue was related to Azure AD login. It was fixed by Microsoft on 5th September 2023.

1 answer

ShaktiSingh-MSFT 13,826 Reputation points Microsoft Employee

2023-09-14T04:47:00.9566667+00:00

Hi Kaarlo Räihä •,

Thanks for sharing the solution with Q&A community.

I'm glad that you were able to resolve your issue and thank you for posting your solution so that others experiencing the same thing can easily reference this! Since the Microsoft Q&A community has a policy that "The question author cannot accept their own answer. They can only accept answers by others ", I'll repost your solution in case you'd like to "Accept " the answer.

Solution adopted is as below:

Issue was related to Azure AD login. It was fixed by Microsoft on 5th September 2023.

Thanks
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How to figure out the reason for Azure Cache Redis memory usage pattern?

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