ahttp_client:connect is taking up 40kb of memory

[robinchew]

Just running the following piece of code will take up about 40,000 bytes of memory.

Conn = case ahttp_client:connect(https, "gassensor.blob.core.windows.net", 443, [
    {active, false}, {verify, verify_none}, {parse_headers, [<<"Location">>]}
]) of
    {ok, C} -> C;
        E ->  print("Azure connection error ~p~n", [E])
    end,

[robinchew]

Note that this memory exhaustion seems to only happen on gassensor.blob.core.windows.net. If you try on mysensor.blob.core.windows.net, it doesn't seem to exibit this problem.

Edit: Oh that's cos 'gassensor' resolves, whereas the other does not.

[petermm]

related in sdkconfig:

#
# mbedTLS
#
CONFIG_MBEDTLS_INTERNAL_MEM_ALLOC=y
# CONFIG_MBEDTLS_DEFAULT_MEM_ALLOC is not set
# CONFIG_MBEDTLS_CUSTOM_MEM_ALLOC is not set
CONFIG_MBEDTLS_ASYMMETRIC_CONTENT_LEN=y
CONFIG_MBEDTLS_SSL_IN_CONTENT_LEN=16384
CONFIG_MBEDTLS_SSL_OUT_CONTENT_LEN=4096
# CONFIG_MBEDTLS_DYNAMIC_BUFFER is not set
# CONFIG_MBEDTLS_DEBUG is not set

and see this table from https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-reference/protocols/mbedtls.html#reducing-heap-usage

So it's somewhat expected I think.. So probably a docs issue, and test using different configs, but I'm no expert..

[petermm]

CONFIG_MBEDTLS_ECP_FIXED_POINT_OPTIM was recently default disabled in esp-idf.

   This configuration option enables optimizations to speedup (about 3 ~ 4 times) the ECP
   fixed point multiplication using pre-computed tables in the flash memory.
   Disabling this configuration option saves flash footprint (about 29KB if all Elliptic Curve selected)
   in the application binary.

There are some suggestions that enabling it will reduce peak memory usage, at the cost of ~29kb of flash.