about warm up

[Li Li]

I want to load full text into an external cache, So I added so codes
in newSearcher where I found the warm up takes place. I add my codes
before solr warm up  which is configed in solrconfig.xml like this:
    <listener event="firstSearcher" class="solr.QuerySenderListener">
      <arr name="queries">
      ...
      </arr>
    </listener>

public void newSearcher(SolrIndexSearcher newSearcher,
SolrIndexSearcher currentSearcher) {
    warmTextCache(newSearcher,warmTextCache,new String[]{"title","content"});

    for (NamedList nlst : (List<NamedList>)args.get("queries")) {

    }
}

in warmTextCache I need a reader to get some docs
        for(int i=0;i<reader.maxDoc();i++){
            if(reader.isDeleted(i)) continue;
            Document doc=reader.document(i);
                    String fullText=doc.get("content");
                    cache.put(i,fullText);
                  }


So I need a reader, When I contruct a reader by myself like:
IndexReader reader=IndexReader.open(...);
Or by core.getSearcher().get().getReader()
Then it will be very slow when I send a query after warm up
I used jstack and found all of the requests are blocked in SolrCore
line 1000  searcherLock.wait();
      // check to see if we can wait for someone else's searcher to be set
      if (onDeckSearchers>0 && !forceNew && _searcher==null) {
        try {
Line 1000          searcherLock.wait();
        } catch (InterruptedException e) {
          log.info(SolrException.toStr(e));
        }
      }
And about 5 minutes later. it's ok.

So How can I get a "safe" reader in this situation?