I stumbled upon this while debugging an unrelated issue. Any help is appreciated and thank you in advance!
The container (and host) is Ubuntu 20.04 and GraphicsMagick (which has a ceiling memory usage variable) is showing the hosts total memory (62.9GB) and not the container’s memory value (29.8GB).
This is the command ran inside the container:
app01:~# gm convert -list resource
Resource Limits (Q16, 64 bits/pixel, 64bit address)
----------------------------------------------------
Disk: Unlimited (MAGICK_LIMIT_DISK)
Files: 256 (MAGICK_LIMIT_FILES)
Map: 125.7GiB (MAGICK_LIMIT_MAP)
Memory: 62.9GiB (MAGICK_LIMIT_MEMORY)
MAGICK_LIMIT_MEMORY is showing the host’s memory amount of 62.9GiB.
What the container shows via free (also htop shows the correct value too)
app01:~# free -h
total used free shared buff/cache available
Mem: 29Gi 1.8Gi 27Gi 0.0Ki 234Mi 27Gi
In this case it would allow GraphicsMagick to blow past the container’s max memory.
Digging into the GraphicsMagick code I think I’ve found (I may be wrong) where it’s pulling the value if that provides any help. Key variable to see is total_memory.
(disclaimer this is an old version of GraphicsMagick mirror I found on Github)
/*
Set Magick resource limits.
*/
#if defined(POSIX)
{
unsigned long
total_memory=0;
# if defined(HAVE_SYSCONF) && defined(_SC_PHYS_PAGES)
{
long
pagesize=-1,
pages=-1;
/*
Compute total physical memory based on number of memory pages,
and page size.
*/
pages=sysconf(_SC_PHYS_PAGES);
pagesize = MagickGetMMUPageSize();
if (pages > 0 && pagesize > 0)
total_memory=((pages+512)/1024)*((pagesize+512)/1024);
(void) LogMagickEvent(ResourceEvent,GetMagickModule(),
"Total physical memory %ld MB (%ld pages and %ld bytes per page)",
total_memory, pages, pagesize);
}
# elif defined(MAGICK_PHYSICAL_MEMORY_COMMAND) && defined(HAVE_POPEN)
{
double
bytes=0;
FILE
*command;
/*
Execute the external command defined by
MAGICK_PHYSICAL_MEMORY_COMMAND to obtain the total physical
memory in bytes. This external command should be quite speedy
or else it will impact the time to start GraphicsMagick.
*/
if ((command = popen(MAGICK_PHYSICAL_MEMORY_COMMAND, "r")) != NULL)
{
if (fscanf(command,"%lf",&bytes) == 1)
total_memory=(bytes/(1024*1024));
(void) pclose(command);
(void) LogMagickEvent(ResourceEvent,GetMagickModule(),
"Total physical memory %ld MB",total_memory);
}
}
# endif
if (total_memory > 0)
{
/*
We are not able to use more than size_t worth of address
space. On 32 bit systems, we can usually only use half or
three quarters of it. Regardless, we need address space
for more than just image data.
*/
size_t
size_t_max = (size_t) ~0UL;
size_t_max /= (1024U*1024U);
max_memory = Min(size_t_max/2-100,total_memory);
max_map = Min(size_t_max/2-100,2*total_memory);
}
}
#endif /* defined(POSIX) */