If SWI-Prolog core detects that tcmalloc is the current allocator and
provides the following additional predicates.
- [nondet]malloc_property(?Property)
- True when Property is a property of the current allocator.
The properties are defined by the allocator. The properties of tcmalloc
are defined in
gperftools/malloc_extension.h:167Documentation
copied from the header.
- ’generic.current_allocated_bytes'(-Int)
- Number of bytes currently allocated by application.
- ’generic.heap_size'(-Int)
- Number of bytes in the heap (= current_allocated_bytes + fragmentation +
freed memory regions).
- ’tcmalloc.max_total_thread_cache_bytes'(-Int)
- Upper limit on total number of bytes stored across all thread caches.
- ’tcmalloc.current_total_thread_cache_bytes'(-Int)
- Number of bytes used across all thread caches.
- ’tcmalloc.central_cache_free_bytes'(-Int)
- Number of free bytes in the central cache that have been assigned to
size classes. They always count towards virtual memory usage, and unless
the underlying memory is swapped out by the OS, they also count towards
physical memory usage.
- ’tcmalloc.transfer_cache_free_bytes'(-Int)
- Number of free bytes that are waiting to be transferred between the
central cache and a thread cache. They always count towards virtual
memory usage, and unless the underlying memory is swapped out by the OS,
they also count towards physical
- ’tcmalloc.thread_cache_free_bytes'(-Int)
- Number of free bytes in thread caches. They always count towards virtual
memory usage, and unless the underlying memory is swapped out by the OS,
they also count towards physical memory usage.
- ’tcmalloc.pageheap_free_bytes'(-Int)
- Number of bytes in free, mapped pages in page heap. These bytes can be
used to fulfill allocation requests. They always count towards virtual
memory usage, and unless the underlying memory is swapped out by the OS,
they also count towards physical memory usage. This property is not
writable.
- ’tcmalloc.pageheap_unmapped_bytes'(-Int)
- Number of bytes in free, unmapped pages in page heap. These are bytes
that have been released back to the OS, possibly by one of the
MallocExtension "Release" calls. They can be used to fulfill allocation
requests, but typically incur a page fault. They always count towards
virtual memory usage, and depending on the OS, typically do not count
towards physical memory usage.
- [det]set_malloc(+Property)
- Set properties described in malloc_property/1.
Currently the only writable property is
tcmalloc.max_total_thread_cache_bytes. Setting an unknown
property raises a domain_error and setting a read-only
property raises a permission_error exception.
- [semidet]thread_idle(:Goal,
+Duration)
- Indicates to the system that the calling thread will idle for some time
while calling Goal as once/1.
This call releases resources to the OS to minimise the footprint of the
calling thread while it waits. Despite the name this predicate is always
provided, also if the system is not configured with tcmalloc or is
single threaded.
Duration is one of
- short
- Calls trim_stacks/0
and, if tcmalloc is used, calls
MallocExtension_MarkThreadTemporarilyIdle() which empties the thread's
malloc cache but preserves the cache itself.
- long
- Calls garbage_collect/0
and trim_stacks/0
and, if tcmalloc is used, calls MallocExtension_MarkThreadIdle() which
releases all thread-specific allocation data structures.