Hello all,
I’m having an issue understanding how to control/limit the size of the WAL as
well as why I’m consuming so much WAL space.
I’m currently migrating a project from redis to ignite and as part of the first
phase, its pretty much lift and shift without optimizing for ignite. In this
case, I’m passing in a handful of large objects to a cache, most of these are
Map<String, String> types, but one is a more complex structure. All of these
objects combined consume a few GB of RAM but the maps themselves may contain
tens of thousands of entries, though at this stage I don’t care if ignite is
aware of these objects, when I retrieve them from the cache I simply pull out
the full object (see code below). I realize this is not ideal, and will be
refactored to work more efficiently in the next phase.
private IgniteCache<String, Serializable> objectCache;
public LookupDataCacheProvider(final Ignite igniteDataGrid)
{
this.igniteDataGrid = igniteDataGrid;
metadataCache =
igniteDataGrid.getOrCreateCache(LookupDataCacheKey.METADATA.getKey());
objectCache =
igniteDataGrid.getOrCreateCache(OBJECT_CACHE_NAME).withKeepBinary();
}
public void setRateCenters(final RateCenters rateCenters)
{
setJavaObject(LookupDataCacheKey.RATE_CENTERS, rateCenters);
}
private <T extends Serializable> void setJavaObject(final LookupDataCacheKey
lookupDataCacheKey, final T value) {
objectCache.put(lookupDataCacheKey.getKey(), value);
}
private <T extends Serializable> T getJavaObject(final LookupDataCacheKey
lookupDataCacheKey, final Class<T> tClass) {
return tClass.cast(objectCache.get(lookupDataCacheKey.getKey()));
}
My problem is that when the largest of these maps get written to the cache, it
fills up the mount we have dedicated to persistent storage, looking at the
directory structure the majority of the space is in WAL archives.
We have a 100G mount for persistence, which we assumed would be plenty for
something that normally fits into a few GB of ram.
So, can anyone point me at something I can use to calculate the size needed for
the WAL based on ignite settings or what settings I really care about?
Additionally, can anyone give me a general reason for why the WAL may get so
massive for such a small set of data (max 4G data in ram, 100gb in WAL before
it runs out of space). Is this just a case of using ignite so wrong that it
doesn’t work? If I were to make the Map<String, String> a cache by itself
rather than a object inside a cache, as a general rule would that be more
likely or less likely to increase WAL usage.
What am I doing wrong that is consuming so much WAL?
