Logging stops on all backend when overloaded for a time

[thales-nascimento]

Describe the bug
Logging stops on all backend when overloaded for a time. After stopped no more messages are produced, even when the overload ceases. By overloaded I mean to drop 99% of the messages.

Platform: STM32H743
Version: tag zephyr-v3.5.0

Additional info:
I have two backends, one logs on UART and other logs to an external flash with filesystem littlefs and file rotation. All my threas are same priority 5.

Workarround: patching log_core.c to trigger the logging thread when above the configured threshold seems to work.
With the workarround the system behaves normally after the overload passes.

KConfigs

#
# Logging
#
CONFIG_LOG=y
CONFIG_LOG_CORE_INIT_PRIORITY=0
CONFIG_LOG_MODE_DEFERRED=y
# CONFIG_LOG_MODE_IMMEDIATE is not set
# CONFIG_LOG_MODE_MINIMAL is not set
# CONFIG_LOG_FRONTEND is not set
# CONFIG_LOG_CUSTOM_HEADER is not set
# CONFIG_LOG_MULTIDOMAIN is not set

#
# Logging levels filtering
#
# CONFIG_LOG_RUNTIME_FILTERING is not set
CONFIG_LOG_DEFAULT_LEVEL=3
CONFIG_LOG_OVERRIDE_LEVEL=0
CONFIG_LOG_MAX_LEVEL=4
# end of Logging levels filtering

#
# Processing
#
CONFIG_LOG_PRINTK=y
CONFIG_LOG_MODE_OVERFLOW=y
# CONFIG_LOG_BLOCK_IN_THREAD is not set
CONFIG_LOG_PROCESS_TRIGGER_THRESHOLD=10
CONFIG_LOG_PROCESS_THREAD=y
CONFIG_LOG_PROCESS_THREAD_STARTUP_DELAY_MS=1000
CONFIG_LOG_PROCESS_THREAD_SLEEP_MS=1000
CONFIG_LOG_PROCESS_THREAD_STACK_SIZE=4096
# CONFIG_LOG_PROCESS_THREAD_CUSTOM_PRIORITY is not set
CONFIG_LOG_BUFFER_SIZE=8192
CONFIG_LOG_TRACE_SHORT_TIMESTAMP=y
# CONFIG_LOG_TIMESTAMP_64BIT is not set
# CONFIG_LOG_SPEED is not set
# end of Processing

#
# Output Formatting
#

#
# Prepend non-hexdump log message with function name
#
# CONFIG_LOG_FUNC_NAME_PREFIX_ERR is not set
# CONFIG_LOG_FUNC_NAME_PREFIX_WRN is not set
# CONFIG_LOG_FUNC_NAME_PREFIX_INF is not set
# CONFIG_LOG_FUNC_NAME_PREFIX_DBG is not set
# end of Prepend non-hexdump log message with function name

# CONFIG_LOG_MIPI_SYST_ENABLE is not set
# CONFIG_LOG_THREAD_ID_PREFIX is not set
# CONFIG_LOG_CUSTOM_FORMAT_SUPPORT is not set
CONFIG_LOG_BACKEND_SHOW_COLOR=y
# CONFIG_LOG_INFO_COLOR_GREEN is not set
CONFIG_LOG_TAG_MAX_LEN=0
CONFIG_LOG_BACKEND_FORMAT_TIMESTAMP=y
# CONFIG_LOG_OUTPUT_FORMAT_LINUX_TIMESTAMP is not set
# CONFIG_LOG_OUTPUT_FORMAT_CUSTOM_TIMESTAMP is not set
# end of Output Formatting

#
# Backends
#
# CONFIG_LOG_BACKEND_FS is not set
# CONFIG_LOG_BACKEND_NET is not set
# CONFIG_LOG_BACKEND_SWO is not set
CONFIG_LOG_BACKEND_UART=y
# CONFIG_LOG_BACKEND_UART_ASYNC is not set
CONFIG_LOG_BACKEND_UART_BUFFER_SIZE=1
CONFIG_LOG_BACKEND_UART_AUTOSTART=y
CONFIG_LOG_BACKEND_UART_OUTPUT_TEXT=y
# CONFIG_LOG_BACKEND_UART_OUTPUT_DICTIONARY is not set
# CONFIG_LOG_BACKEND_UART_OUTPUT_CUSTOM is not set
CONFIG_LOG_BACKEND_UART_OUTPUT_DEFAULT=0
# CONFIG_LOG_BACKEND_IPC_SERVICE is not set
# end of Backends

#
# Misc
#
CONFIG_LOG_DOMAIN_ID=0
CONFIG_LOG_USE_VLA=y
# CONFIG_LOG_ALWAYS_RUNTIME is not set
# CONFIG_LOG_FMT_SECTION is not set
# CONFIG_LOG_USE_TAGGED_ARGUMENTS is not set
# CONFIG_LOG_MEM_UTILIZATION is not set
CONFIG_LOG_FAILURE_REPORT_PERIOD=1000
# end of Misc

CONFIG_LOG_OUTPUT=y
# end of Logging

Expected behavior
Messages should be dropped as necessary but the logging system should remain operational.

Impact
minor, patch works for me.

Environment

• OS: Linux
• Toolchain: Zephyr sdk 0.16.3
• Zephyr 3.5.0

[github-actions]

Hi @thales-nascimento! We appreciate you submitting your first issue for our open-source project. 🌟

Even though I'm a bot, I can assure you that the whole community is genuinely grateful for your time and effort. 🤖💙

[pdgendt]

Can you submit your fix as a PR?